Protective effects of butyrate on intestinal ischemia–reperfusion injury in rats

Effects of butyrate on intestinal ischemia-reperfusion injury via the HMGB1-TLR4-MyD88 signaling pathway

BACKGROUND

This study combined bioinformatics and experimental verification in a mouse model of intestinal ischemia-reperfusion injury (IRI) to explore the protection mechanism exerted by butyrate against IRI.

METHODS

GeneCards, Bioinformatics Analysis Tool for Molecular Mechanisms of Traditional Chinese Medicine and GSE190581 were used to explore the relationship between butyrate and IRI and aging. Protein-protein interaction networks involving butyrate and IRI were constructed via the STRING database, with hub gene analysis performed through Cytoscape. Functional enrichment analysis was conducted on intersection genes. A mouse model of IRI was established, followed by direct arterial injection of butyrate. The experiment comprised five groups: normal, sham, model, vehicle, low-dose butyrate, and high-dose butyrate. Intestinal tissue observation was done via transmission electron microscopy (TEM), histological examination via hematoxylin and eosin (H&E) staining, tight junction proteins detection via immunohistochemistry, and Western blot analysis of hub genes. Drug-target interactions were evaluated through molecular docking.

RESULTS

Butyrate protected against IRI by targeting 458 genes, including HMGB1 and TLR4. Toll-like receptor pathway was implicated. Butyrate improved intestinal IRI by reducing mucosal damage, increasing tight junction proteins, and lowering levels of HMGB1, TLR4, and MyD88. Molecular docking showed strong binding energies between butyrate and HMGB1 (-3.7 kcal/mol) and TLR4 (-3.8 kcal/mol).

CONCLUSIONS

According to bioinformatics predictions, butyrate mitigates IRI via multiple-target and multiple-channel mechanisms. The extent of IRI can be reduced by butyrate through the inhibition of the HMGB1-TLR4-MyD88 signaling pathway, which is related to senescence.

The Role of Gut Microbiome-Derived Short-Chain Fatty Acid Butyrate in Hepatobiliary Diseases

The short-chain fatty acid butyrate, produced from fermentable carbohydrates by gut microbiota in the colon, has multiple beneficial effects on human health. At the intestinal level, butyrate regulates metabolism, helps in the transepithelial transport of fluids, inhibits inflammation, and induces the epithelial defense barrier. The liver receives a large amount of short-chain fatty acids via the blood flowing from the gut via the portal vein. Butyrate helps prevent nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, inflammation, cancer, and liver injuries. It ameliorates metabolic diseases, including insulin resistance and obesity, and plays a direct role in preventing fatty liver diseases. Butyrate has different mechanisms of action, including strong regulatory effects on the expression of many genes by inhibiting the histone deacetylases and modulating cellular metabolism. The present review highlights the wide range of beneficial therapeutic and unfavorable adverse effects of butyrate, with a high potential for clinically important uses in several liver diseases.

Chronic Mesenteric Ischemia Intestinal Dysbiosis Resolves after Revascularization

Objective

Chronic mesenteric ischemia (CMI) is a debilitating condition arising from intestinal malperfusion from mesenteric artery stenosis or occlusion. Mesenteric revascularization has been the standard of care but can result in substantial morbidity and mortality. Most of the perioperative morbidity has been secondary to postoperative multiple organ dysfunction, potentially from ischemia-reperfusion injury. The intestinal microbiome is a dense community of microorganisms in the gastrointestinal tract that help regulate pathways ranging from nutritional metabolism to the immune response. We hypothesized that patients with CMI will have microbiome perturbations that contribute to this inflammatory response and could potentially normalize in the postoperative period.

Methods

We performed a prospective study of patients with CMI who had undergone mesenteric bypass and/or stenting from 2019 to 2020. Stool samples were collected at three time points: preoperatively at the clinic, perioperatively within 14 days after surgery, and postoperatively at the clinic at >30 days after revascularization. Stool samples from healthy controls were used for comparison. The microbiome was measured using 16S rRNA sequencing on an Illumina-MiSeq sequence platform and analyzed using the QIIME2 (quantitative insights into microbial ecology 2)-DADA2 bioinformatics pipeline with the Silva database. Beta-diversity was analyzed using a principal coordinates analysis and permutational analysis of variance. Alpha-diversity (microbial richness and evenness) was compared using the nonparametric Mann-Whitney U test. Microbial taxa unique to CMI patients vs controls were identified using linear discriminatory analysis effect size analysis. P < .05 was considered statistically significant.

Results

Eight patients with CMI had undergone mesenteric revascularization (25% men; average age, 71 years). Nine healthy controls were also analyzed (78% men; average age, 55 years). Bacterial alpha-diversity (number of operational taxonomic units) was dramatically reduced preoperatively compared with that of the controls (P = .03). However, revascularization partially restored the species richness and evenness in the perioperative and postoperative phases. Beta-diversity was only different between the perioperative and postoperative groups (P = .03). Further analyses revealed increased abundance of Bacteroidetes and Clostridia taxa preoperatively and perioperatively compared with the controls, which was reduced during the postoperative period.

Conclusions

The results from the present study have shown that patients with CMI have intestinal dysbiosis that resolves after revascularization. The intestinal dysbiosis is characterized by the loss of alpha-diversity, which is restored perioperatively and maintained postoperatively. This microbiome restoration demonstrates the importance of intestinal perfusion to sustain gut homeostasis and suggests that microbiome modulation could be a possible intervention to ameliorate acute and subacute postoperative outcomes in these patients.

Clostridium butyricum improves the intestinal health of goats by regulating the intestinal microbial community

Clostridium butyricum, as a probiotic with a variety of active products, has been widely used to improve the intestinal health of humans and animals. Previous studies had demonstrated that Clostridium butyricum exhibited potential protective and positive effects in human disease research and animal production by producing a variety of beneficial substances, such as intestinal inflammation, the intestinal epithelial barrier, metabolic diseases, and regulation of the gut microbiota. Therefore, we hypothesized that dietary Clostridium butyricum supplementation could improve gut health in fattening goats by modulating gut microbiota. However, it is unclear whether Clostridium butyricum can reach the intestine through the rumen, so 15 healthy Albas goats were selected and randomly divided into 3 treatments with 5 replicates in each group. The groups were divided as follows: control group (CON: basal diet), rumen-protected Clostridium butyricum group (RPCB: basal diet plus 1.0 × 10⁹ CFU/kg Clostridium butyricum coated with hydrogenated fat), and Clostridium butyricum group (CB: basal diet plus 1.0 × 10⁹ CFU/kg Clostridium butyricum). The experiment was slaughtered after a 70-day growth test, and the jejunal mucosa and intestinal contents of the goats were collected to determine tight junction proteins related genes expression and 16S rDNA microbial sequencing analysis to evaluate the intestine health. The results showed that dietary supplementation with Clostridium butyricum significantly increased the expression of the Claudin-4 gene of the jejunal mucosa (P < 0.05) and had a trend toward a significant increase in the Occludin gene (0.05 < P < 0.10). However, Clostridium butyricum had no significant effect on the expression of intestinal inflammatory factors (P > 0.10). In addition, the relative fractionation of Clostridium and Clostridiaceae_unclassified in the gut microbiota at the genus level decreased significantly compared with controls (P < 0.05). The results of the analysis of the level of Clostridium species showed that Clostridium butyricum only existed in the treatment group. And the correlation results showed that Occludin and Claudin-4 genes were positively correlated with Sharppea and Clostridium butyricum, and negatively correlated with Clostridium (P < 0.05). Supplementing Clostridium butyricum in the diet did not significantly affect the intestinal immune function of goats, while regulation of the intestinal microbiota was associated with improving the intestinal epithelial barrier.

Propionic Acid, Induced in Gut by an Inulin Diet, Suppresses Inflammation and Ameliorates Liver Ischemia and Reperfusion Injury in Mice

Liver ischemia and reperfusion injury (IRI) is one of the obstacles in liver surgery such as liver resection and transplantation. In this study, we investigated the preventive effect on mouse liver IRI by feeding mice with inulin, which is a heterogeneous blend of indigestible fructose polymer. Mice were fed either a control ordinary diet (CD) or an inulin diet (ID) containing 5% inulin in the CD, for 14 days before the ischemia and reperfusion (IR) maneuver. IR induced-liver damages were significantly ameliorated in the ID group, compared with those in the CD group. Feeding mice with an ID, but not a CD, elevated levels of Bacteroidetes among gut microbiota, and especially increased Bacteroides acidifaciens in mouse feces, which resulted in significant elevation of short-chain fatty acids (SCFAs) in the portal vein of mice. Among SCFAs, propionic acid (PA) was most significantly increased. The microbial gene functions related to PA biosynthesis were much higher in the fecal microbiome of the ID group compared to the CD. However, the action of PA on liver IRI has not been yet clarified. Direct intraperitoneal administration of PA alone prior to the ischemia strongly suppressed liver cell damages as well as inflammatory responses caused by liver IR. Furthermore, PA suppressed the secretion of inflammatory cytokines from peritoneal macrophages stimulated in vitro through TLR-4 with high-mobility group box 1 protein (HMGB-1), known to be released from apoptotic liver cells during the IR insult. The present study shows that PA may play a key role in the inulin-induced amelioration of mouse liver IRI.

Propionate alleviates palmitic acid-induced endoplasmic reticulum stress by enhancing autophagy in calf hepatic cells

Negative energy balance-induced high blood concentrations of free fatty acids during the early postpartum period in dairy cows is a major cause of liver injury. Cows in severe negative energy balance often have suboptimal intakes of feed, which contributes to shortfalls in production of ruminal propionate and circulating glucose. Although increasing propionate production by the rumen through feed additives such as propylene glycol is effective in helping cows alleviate the shortfall in dietary energy supply, mechanisms whereby propionate affects liver function beyond gluconeogenesis are unknown. Therefore, the objective of this study was to investigate whether propionate could protect calf hepatic cells from palmitic acid (PA)-induced lipotoxicity and the underlying mechanisms. Calf hepatic cells were isolated from 5 healthy calves (1 d old, female, 30-40 kg, fasting) and treated with various concentrations of PA (0, 100, 200, or 400 μM) and propionate (0, 1, 2, or 4 mM) after being administered with or without autophagic inhibitor. Propionate enhanced autophagic activity in calf hepatic cells, as indicated by elevated expression of autophagy markers LC3-II (microtubule-associated protein 1 light chain 3-II, encoded by MAP1LC3) and decreased expression of SQSTM1 (sequestosome-1, also called p62). Conversely, PA suppressed autophagic activity and decreased cell viability, which was improved by propionate in calf hepatic cells. In addition, propionate decreased the phosphorylation of proteins EIF2AK3 (kinase R/PKR like ER kinase) and ERN1 (inositol-requiring enzyme 1α) and cleaved ATF6 (activating transcription factor 6) in PA-treated calf hepatic cells, indicating the suppression effect of propionate on endoplasmic reticulum (ER) stress. However, inhibition of autophagic activity by chloroquine or bafilomycin A1 impede the beneficial effects of propionate on ER stress and cell viability. These results demonstrated that propionate alleviates ER stress and elevates cell viability in PA-treated calf hepatic cells by enhancing autophagy, which implies that autophagy may be a promising target in improving liver injury of dairy cows during transition period.

Consideration of Gut Microbiome in Murine Models of Diseases

The gut microbiome (GM), a complex community of bacteria, viruses, protozoa, and fungi located in the gut of humans and animals, plays significant roles in host health and disease. Animal models are widely used to investigate human diseases in biomedical research and the GM within animal models can change due to the impact of many factors, such as the vendor, husbandry, and environment. Notably, variations in GM can contribute to differences in disease model phenotypes, which can result in poor reproducibility in biomedical research. Variation in the gut microbiome can also impact the translatability of animal models. For example, standard lab mice have different pathogen exposure experiences when compared to wild or pet store mice. As humans have antigen experiences that are more similar to the latter, the use of lab mice with more simplified microbiomes may not yield optimally translatable data. Additionally, the literature describes many methods to manipulate the GM and differences between these methods can also result in differing interpretations of outcomes measures. In this review, we focus on the GM as a potential contributor to the poor reproducibility and translatability of mouse models of disease. First, we summarize the important role of GM in host disease and health through different gut–organ axes and the close association between GM and disease susceptibility through colonization resistance, immune response, and metabolic pathways. Then, we focus on the variation in the microbiome in mouse models of disease and address how this variation can potentially impact disease phenotypes and subsequently influence research reproducibility and translatability. We also discuss the variations between genetic substrains as potential factors that cause poor reproducibility via their effects on the microbiome. In addition, we discuss the utility of complex microbiomes in prospective studies and how manipulation of the GM through differing transfer methods can impact model phenotypes. Lastly, we emphasize the need to explore appropriate methods of GM characterization and manipulation.

The Anti-Inflammatory Effect and Mucosal Barrier Protection of Clostridium butyricum RH2 in Ceftriaxone-Induced Intestinal Dysbacteriosis

This study aimed at determining the beneficial effect of Clostridium butyricum (CB) RH2 on ceftriaxone-induced dysbacteriosis. To this purpose, BALB/c mice were exposed to ceftriaxone (400 mg/ml) or not (control) for 7 days, and administered a daily oral gavage of low-, and high-dose CB RH2 (10⁸ and 10¹⁰ CFU/ml, respectively) for 2 weeks. CB RH2 altered the diversity of gut microbiota, changed the composition of gut microbiota in phylum and genus level, decreased the F/B ratio, and decreased the pro-inflammatory bacteria (Deferribacteres, Oscillibacter, Desulfovibrio, Mucispirillum and Parabacteroides) in ceftriaxone-treated mice. Additionally, CB RH2 improved colonic architecture and intestinal integrity by improving the mucous layer and the tight junction barrier. Furthermore, CB RH2 also mitigated intestinal inflammation through decreasing proinflammatory factors (TNF-α and COX-2) and increasing anti-inflammatory factors (IL-10). CB RH2 had direct effects on the expansion of CD4⁺ T cells in Peyer’s patches (PPs) in vitro, which in turn affected their immune response upon challenge with ceftriaxone. All these data suggested that CB RH2 possessed the ability to modulate the intestinal mucosal and systemic immune system in limiting intestinal alterations to relieve ceftriaxone-induced dysbacteriosis.

Importance of "muscle" and "intestine" training before major HPB surgery: A review

Major hepato-pancreato-biliary (HPB) surgery is one of the most invasive abdominal surgeries. Through the experiences of several clinical trials, including those involving patients undergoing major HPB surgery, we have recognized the importance of "muscle" and "intestine" training before surgery. This review article summarizes the results of our clinical trials, specifically focusing on the importance of "muscle" and "intestine". The patients with low skeletal muscle mass or those with low functional exercise capacity showed a significantly worse postoperative course and poor long-term survival after surgery for HPB malignancy. The introduction of prehabilitation (preoperative physical and nutritional support) improved nutritional status and functional exercise capacity, even in patients with malignancy. Daily physical activity was correlated with nutritional status before surgery. These results indicated the usefulness of prehabilitation. The intestinal microenvironment, which is extrapolated from the fecal concentrations of short-chain fatty acids (SCFAs), showed a significant association with the incidence of surgery-induced bacterial translocation and postoperative infectious complications (POICs). The use of perioperative synbiotics not only increased the fecal levels of SCFAs but also prevented the incidence of POICs. A recent study also indicated that there are correlations between muscle mass and the intestinal microenvironment. Further investigation is required to determine the best "muscle" and "intestine" training protocol to improve the outcomes of major HPB surgeries.

Effect of Clostridium butyricum and Butyrate on Intestinal Barrier Functions: Study of a Rat Model of Severe Acute Pancreatitis With Intra-Abdominal Hypertension

BACKGROUND/AIMS

Severe acute pancreatitis (SAP) is associated with intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS), but treatment of these conditions is difficult. We studied a rat model of SAP + IAH to determine the effect of oral administration of Clostridium butyricum and butyrate (its major metabolite) on intestinal barrier functions.

METHODS

A total of 48 rats were assigned to four groups, with 12 rats per group: Sham, SAP+IAH, SAP+IAH+C. butyricum, and SAP + IAH + butyrate. SAP was induced by sodium taurocholate infusion into the biliopancreatic duct, intra-abdominal pressure (IAP), mortality was measured 24 h later, and then rats were euthanized. The plasma levels of several markers [amylase, diamine oxidase (DAO), fluorescein isothiocyanate (FITC)-dextran, tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-1β, IL-12, lipopolysaccharide (LPS)] and fecal butyric acid level were determined. The pancreas and intestine were examined using histology, and RT-PCR and Western blotting of intestinal tissues were used to measure the expression of six markers {tight junction proteins [zonula occludens protein-1 (ZO-1), claudin-1, claudin-2, occluding], matrix metalloproteinase 9 [MMP9], and TNF-α}. The gut flora of the rats was examined by 16S rRNA sequencing.

RESULTS

Induction of SAP + IAH altered several functions of the intestinal barrier, and enhanced intestinal permeability, decreased the levels of ZO-1, claudin-1, occludin, the richness and diversity of the microflora community, the relative abundance (RA) of Firmicutes, and the number of probiotic organisms. However, induction of SAP+IAH increased the expression of claudin-2, MMP9, and TNF-α, and the RA of Proteobacteria and pathogens in the feces. Rats that received oral C. butyricum or butyrate had reduced intestinal injury and plasma levels of DAO, LPS, and inflammatory cytokines.

CONCLUSION

This study of rats with SAP+IAH indicated that oral dosing of C. butyricum or butyrate reduced intestinal injury, possibly by altering the functions of the intestinal mucosal barrier.

Intestinal TLR9 deficiency exacerbates hepatic IR injury via altered intestinal inflammation and short-chain fatty acid synthesis

Mice deficient in intestinal epithelial TLR9 develop small intestinal Paneth cell hyperplasia and higher Paneth cell IL-17A levels. Since small intestinal Paneth cells and IL-17A play critical roles in hepatic ischemia reperfusion (IR) injury, we tested whether mice lacking intestinal TLR9 have increased hepatic IR injury. Mice lacking intestinal TLR9 had profoundly increased liver injury after hepatic IR compared to WT mice with exacerbated hepatocyte necrosis, apoptosis, neutrophil infiltration, and inflammatory cytokine generation. Moreover, we observed increased small intestinal inflammation and apoptosis after hepatic IR in intestinal TLR9 deficient mice. As a potential explanation for increased hepatic IR injury, fecal short-chain fatty acids butyrate and propionate levels were lower in intestinal TLR9 deficient mice. Suggesting a potential therapy for hepatic IR, exogenous administration of butyrate or propionate protected against hepatic IR injury in intestinal TLR9 deficient mice. Mechanistically, butyrate induced small intestinal IL-10 expression and downregulated the claudin-2 expression. Finally, IL-10 neutralization abolished the protective effects of butyrate against hepatic IR injury. Our studies show intestinal TLR9 deficiency results in exacerbated hepatic IR injury with increased small intestinal apoptosis and inflammation. Furthermore, short-chain fatty acids butyrate and propionate protect against hepatic IR injury and intestinal apoptosis/inflammation in intestinal TLR9 deficient mice.

Acute Effects of Butyrate on Induced Hyperpermeability and Tight Junction Protein Expression in Human Colonic Tissues

Intact intestinal barrier function is essential for maintaining intestinal homeostasis. A dysfunctional intestinal barrier can lead to local and systemic inflammation through translocation of luminal antigens and has been associated with a range of health disorders. Butyrate, a short-chain fatty acid derived from microbial fermentation of dietary fibers in the colon, has been described as an intestinal barrier-strengthening agent, although mainly by using in vitro and animal models. This study aimed to investigate butyrate’s ability to prevent intestinal hyperpermeability, induced by the mast cell degranulator Compound 48/80 (C48/80), in human colonic tissues. Colonic biopsies were collected from 16 healthy subjects and intestinal permeability was assessed by Ussing chamber experiments. Furthermore, the expression levels of tight junction-related proteins were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Pre-treatment with 5 mM butyrate or 25 mM butyrate did not protect the colonic tissue against induced paracellular or transcellular hyperpermeability, measured by FITC-dextran and horseradish peroxidase passage, respectively. Biopsies treated with 25 mM butyrate prior to stimulation with C48/80 showed a reduced expression of claudin 1. In conclusion, this translational ex vivo study did not demonstrate an acute protective effect of butyrate against a chemical insult to the intestinal barrier in healthy humans.

Sodium Butyrate Ameliorates Intestinal Injury and Improves Survival in a Rat Model of Cecal Ligation and Puncture-Induced Sepsis

Sepsis is a life-threatening condition with a high rate of mortality. Unfortunately, very few therapies can improve outcomes in patients with sepsis. Butyrate, which is the most potent histone deacetylase (HDAC) inhibitor among short-chain fatty acids, exerts anti-inflammatory effects in a variety of inflammatory diseases. Butyrate might thus be valuable in the treatment of sepsis, in which inhibition of overwhelming cytokine release is vitally important. Sepsis was induced in 7- to 8-week-old Sprague-Dawley rats by cecal ligation and puncture (CLP) with a 21-g double-puncture technique. Rats received an intravenous injection of normal saline (vehicle) or sodium butyrate (200 mg/kg) after CLP and were sacrificed 12 h later. Hematoxylin and eosin staining was performed to observe the intestinal mucosal morphology. RT-PCR and ELISA were used to determine the intestinal inflammatory response in vivo. Intestinal permeability was evaluated by measuring fluorescein isothiocyanate dextran (FD-4) absorption in vivo, and tight junction protein expression was examined by western blot. NF-κB p65 activities were assessed by western blot and immunohistochemistry. Sodium butyrate treatment improved the survival rate of CLP rats and alleviated sepsis-induced intestinal mucosal injury. Proinflammatory cytokine expression was lower in butyrate-treated rats than in the vehicle group. FD-4 leakage from the intestinal tract was reduced, and the expression levels of the tight junction proteins claudin-1 and ZO-1 were also restored in rats that received sodium butyrate treatment. These effects were associated with less NF-κB p65 nuclear translocation, whereas the expression of Iκ-Bα was not affected or even increased. Sodium butyrate mitigates the inflammatory response and maintains intestinal barrier function in polymicrobial sepsis partly through inhibition of NF-κB activation and may serve as a novel therapy for sepsis.

The Gut Microbiota in Cardiovascular Disease and Arterial Thrombosis

The gut microbiota has emerged as a contributing factor in the development of atherosclerosis and arterial thrombosis. Metabolites from the gut microbiota, such as trimethylamine N-oxide and short chain fatty acids, were identified as messengers that induce cell type-specific signaling mechanisms and immune reactions in the host vasculature, impacting the development of cardiovascular diseases. In addition, microbial-associated molecular patterns drive atherogenesis and the microbiota was recently demonstrated to promote arterial thrombosis through Toll-like receptor signaling. Furthermore, by the use of germ-free mouse models, the presence of a gut microbiota was shown to influence the synthesis of endothelial adhesion molecules. Hence, the gut microbiota is increasingly being recognized as an influencing factor of arterial thrombosis and attempts of dietary pre- or probiotic modulation of the commensal microbiota, to reduce cardiovascular risk, are becoming increasingly significant.

Protective Effect of Nigella Sativa in an Animal Model of Colon Anastomosis With Ischemia/Reperfusion Injury

Objective:

Anastomotic leaks are one of the chief complications after gastrointestinal surgery. The aim of this study was to evaluate whether Nigella sativa administration protects against ischemia/reperfusion injury on healing of colonic anastomosis in rats.

Method:

Thirty male Wistar albino rats, weighing between 200 and 240 g, were used in the study. They were randomly divided into three groups (n = 10 for each group): Anastomosis (group 1), anastomosis and ischemia/reperfusion injury (group 2), and treatment group of anastomosis, ischemia/reperfusion injury, and Nigella sativa (group 3). After 7 days, serum, plasma, and colonic tissue were obtained and then all rats were sacrificed. Tissue and serum level of total oxidant status, total antioxidant status, total thiol levels, hydroxyproline, interleukin-6, and TNF-alpha were determined and specimens were histopathologically evaluated.

Results:

In the Nigella sativa treated rats, serum hydroxyproline levels were significantly higher, while tissue levels were significantly lower than those seen in group 1 and group 2 (P = 0.007, P = 0.01, respectively). In the Nigella sativa group, the serum levels of TNF-α were significantly lower than those seen in group 1 and 2 (P = 0.001). Also, in group 3, the tissue IL-6 level was significantly higher than that seen in group 1 and group 2 (P = 0.009). The histopathologic analysis showed less edema and inflammatory cell infiltration in the Nigella sativa treated group, as well as a statistically significant difference according to the Chiu classification (P &lt; 0.05).

Conclusion:

The results of this study indicate that Nigella sativa has a protective and therapeutic effect against ischemia/reperfusion injury on the healing of colonic anastomosis in rats.

Cell-Based Drug Delivery and Use of Nano-and Microcarriers for Cell Functionalization

Cell functionalization with recently developed various nano- and microcarriers for therapeutics has significantly expanded the application of cell therapy and targeted drug delivery for the effective treatment of a number of diseases. The aim of this progress report is to review the most recent advances in cell-based drug vehicles designed as biological transporter platforms for the targeted delivery of different drugs. For the design of cell-based drug vehicles, different pathways of cell functionalization, such as covalent and noncovalent surface modifications, internalization of carriers are considered in greater detail together with approaches for cell visualization in vivo. In addition, several animal models for the study of cell-assisted drug delivery are discussed. Finally, possible future developments and applications of cell-assisted drug vehicles toward targeted transport of drugs to a designated location with no or minimal immune response and toxicity are addressed in light of new pathways in the field of nanomedicine.

Modulation of Intestinal Microbiome Prevents Intestinal Ischemic Injury

Background: Butyrate protects against ischemic injury to the small intestine by reducing inflammation and maintaining the structure of the intestinal barrier, but is expensive, short-lived, and cannot be administered easily due to its odor. Lactate, both economical and more palatable, can be converted into butyrate by the intestinal microbiome. This study aimed to assess in a rat model whether lactate perfusion can also protect against intestinal ischemia.

Materials and Methods: Rat intestinal segments were loaded in an in vitro bowel perfusion device, and water absorption or secretion was assessed based on fluorescence of FITC-inulin, a fluorescent marker bound to a biologically inert sugar. Change in FITC concentration was used as a measure of ischemic injury, given the tendency of ischemic cells to retain water. Hematoxylin and eosin-stained sections at light level microscopy were examined to evaluate intestinal epithelium morphology. Comparisons between the data sets were paired Student t-tests or ANOVA with p < 0.05 performed on GraphPad.

Results: Lactate administration resulted in a protective effect against intestinal ischemia of similar magnitude to that observed with butyrate. Both exhibited approximately 1.5 times the secretion exhibited by control sections (p = 0.03). Perfusion with lactate and methoxyacetate, a specific inhibitor of lactate-butyrate conversion, abolished this effect (p = 0.09). Antibiotic treatment also eliminated this effect, rendering lactate-perfused sections similar to control sections (p = 0.72). Perfusion with butyrate and methoxyacetate did not eliminate the observed increased secretion, which indicates that ischemic protection was mediated by microbial conversion of lactate to butyrate (p = 0.71).

Conclusions: Lactate's protective effect against intestinal ischemia due to microbial conversion to butyrate suggests possible applications in the transplant setting for reducing ischemic injury and ameliorating intestinal preservation during transport.

Orthogonal Comparison of GC-MS and 1H NMR Spectroscopy for Short Chain Fatty Acid Quantitation

Short chain fatty acids (SCFAs) are important regulators of host physiology and metabolism and may contribute to obesity and associated metabolic diseases. Interest in SCFAs has increased in part due to the recognized importance of how production of SCFAs by the microbiota may signal to the host. Therefore, reliable, reproducible, and affordable methods for SCFA profiling are required for accurate identification and quantitation. In the current study, four different methods for SCFA (acetic acid, propionic acid, and butyric acid) extraction and quantitation were compared using two independent platforms including gas chromatography coupled with mass spectrometry (GC-MS) and 1H nuclear magnetic resonance (NMR) spectroscopy. Sensitivity, recovery, repeatability, matrix effect, and validation using mouse fecal samples were determined across all methods. The GC-MS propyl esterification method exhibited superior sensitivity for acetic acid and butyric acid measurement (LOD < 0.01 μg mL-1, LOQ < 0.1 μg mL-1) and recovery accuracy (99.4%-108.3% recovery rate for 100 μg mL-1 SCFA mixed standard spike in and 97.8%-101.8% recovery rate for 250 μg mL-1 SCFAs mixed standard spike in). NMR methods by either quantitation relative to an internal standard or quantitation using a calibration curve yielded better repeatability and minimal matrix effects compared to GC-MS methods. All methods generated good calibration curve linearity (R2 > 0.99) and comparable measurement of fecal SCFA concentration. Lastly, these methods were used to quantitate fecal SCFAs obtained from conventionally raised (CONV-R) and germ free (GF) mice. Results from global metabolomic analysis of feces generated by 1H NMR and bomb calorimetry were used to further validate these approaches.

Gamma-Aminobutyric Acid Increases the Production of Short-Chain Fatty Acids and Decreases pH Values in Mouse Colon

Gamma-Aminobutyric acid (GABA) could regulate physiological functions in the gastrointestinal tract. The present study aimed to investigate the effect of GABA on colon health in mice. The female Kunming mice were given GABA at doses of 5, 10, 20 and 40 mg/kg/d for 14 days. Afterwards, the short-chain fatty acids (SCFAs) concentrations, pH values, colon index, colon length and weight of colonic and cecal contents were determined to evaluate the effects of GABA on colon health. The results showed that intake of GABA could increase the concentrations of acetate, propionate, butyrate and total SCFAs in colonic and cecal contents, as well as the weight of colonic and cecal contents. The colon index and length of the 40 mg/kg/d GABA-treated group were significantly higher than those of the control group (p < 0.05). In addition, decrease of pH values in colonic and cecal contents was also observed. These results suggest that GABA may improve colon health.

Lipoxin A4 Preconditioning Attenuates Intestinal Ischemia Reperfusion Injury through Keap1/Nrf2 Pathway in a Lipoxin A4 Receptor Independent Manner

Oxidative stress plays a critical role in the pathogenesis of intestinal ischemia reperfusion (IIR) injury. Enhancement in endogenous Lipoxin A4 (LXA4), a potent antioxidant and mediator, is associated with attenuation of IIR. However, the effects of LXA4 on IIR injury and the potential mechanisms are unknown. In a rat IIR (ischemia 45 minutes and subsequent reperfusion 6 hours) model, IIR caused intestinal injury, evidenced by increased serum diamine oxidase, D-lactic acid, intestinal-type fatty acid-binding protein, and the oxidative stress marker 15-F2t-Isoprostane. LXA4 treatment significantly attenuated IIR injury by reducing mucosal 15-F2t-Isoprostane and elevating endogenous antioxidant superoxide dismutase activity, accompanied with Keap1/Nrf2 pathway activation. Meanwhile, LXA4 receptor antagonist Boc-2 reversed the protective effects of LXA4 on intestinal injury but failed to affect the oxidative stress and the related Nrf2 pathway. Furthermore, Nrf2 antagonist brusatol reversed the antioxidant effects conferred by LXA4 and led to exacerbation of intestinal epithelium cells oxidative stress and apoptosis, finally resulting in a decrease of survival rate of rat. Meanwhile, LXA4 pretreatment upregulated nuclear Nrf2 level and reduced hypoxia/reoxygenation-induced IEC-6 cell damage and Nrf2 siRNA reversed this protective effect of LXA4 in vitro. In conclusion, these findings suggest that LXA4 ameliorates IIR injury by activating Keap1/Nrf2 pathway in a LXA4 receptor independent manner.