Unconjugated bilirubin alleviates experimental ulcerative colitis by regulating intestinal barrier function and immune inflammation

Integrated annotation prioritizes metabolites with bioactivity in inflammatory bowel disease

Microbial biochemistry is central to the pathophysiology of inflammatory bowel diseases (IBD). Improved knowledge of microbial metabolites and their immunomodulatory roles is thus necessary for diagnosis and management. Here, we systematically analyzed the chemical, ecological, and epidemiological properties of ~82k metabolic features in 546 Integrative Human Microbiome Project (iHMP/HMP2) metabolomes, using a newly developed methodology for bioactive compound prioritization from microbial communities. This suggested >1000 metabolic features as potentially bioactive in IBD and associated ~43% of prevalent, unannotated features with at least one well-characterized metabolite, thereby providing initial information for further characterization of a significant portion of the fecal metabolome. Prioritized features included known IBD-linked chemical families such as bile acids and short-chain fatty acids, and less-explored bilirubin, polyamine, and vitamin derivatives, and other microbial products. One of these, nicotinamide riboside, reduced colitis scores in DSS-treated mice. The method, MACARRoN, is generalizable with the potential to improve microbial community characterization and provide therapeutic candidates.

Nanomedicine-mediated drug delivery for potential treatment of inflammatory bowel disease: a narrative review

Background & aims: Inflammatory bowel disease (IBD) is a condition characterized by chronic inflammation of the gastrointestinal tract, manifesting as either Crohn's disease (CrD) or ulcerative colitis (UC). Current treatment options for CrD and UC primarily focus on symptom management. In recent years, advancements in nanotechnology have increased the clinical applicability of nanoparticles (NPs) in treating IBD. This review explores the current research on NP-mediated drug-delivery systems for IBD treatment and assesses its advantages and limitations. Results: The authors examine diverse nanomedicine applications for IBD and address the current challenges and prospects in the field to advance nanomediated therapies in the future. Conclusion: Innovative NP-based treatment strategies promise a reliable and effective approach to IBD management.

The isothiocyanate sulforaphane prevents mitochondrial impairment and neuroinflammation in the human dopaminergic SH-SY5Y and in the mouse microglial BV2 cells: role for heme oxygenase-1

Sulforaphane (SFN) promotes protective effects in different cell types. Nonetheless, it remains to be clarified by which mechanism SFN exerts benefits in mammalian cells. Mitochondria are a major source of adenosine triphosphate (ATP) and reactive species in nucleated cells. Mitochondrial impairment result in cellular redox biology disruption, bioenergetic status collapse, and inflammation. Evidence suggest that mitochondrial dysfunction plays a role in neurological disorders. Since a cure was not discovered yet to some of these diseases, investigating strategies to promote mitochondrial protection is pharmacologically relevant and may improve life quality of patients suffering from these maladies. Natural molecules, such as SFN, are potent inducers of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and, consequently, stimulate the expression of genes whose products, such as heme oxygenase-1 (HO-1), induce cytoprotective actions in mammalian tissues. In this work, we investigated whether SFN (5 µM) would be capable to prevent the dysfunctions caused by chlorpyrifos (CPF) on the human dopaminergic SH-SY5Y cells. Moreover, we examined the effects of a pretreatment with SFN at the same concentration on the mouse microglial BV2 cells stimulated by lipopolysaccharide (LPS) in an experimental model of neuroinflammation. SFN prevented the mitochondrial impairment and the neuroinflammation caused by the chemical stressors in both cell types. Inhibition of heme oxygenase-1 (HO-1) suppressed the mitochondrial protection and anti-inflammatory action afforded by SFN in this experimental model. Overall, SFN promoted cytoprotection by a mechanism dependent on the HO-1 enzyme in the SH-SY5Y and BV2 cells.

Development of Paeonol Liposomes: Design, Optimization, in vitro and in vivo Evaluation

BACKGROUND

Ulcerative colitis (UC) is one of the intractable diseases recognized by the World Health Organization, and paeonol has been proven to have therapeutic effects. However, the low solubility of paeonol limits its clinical application. To prepare and optimize paeonol liposome, study its absorption mechanism and the anti-inflammatory activity in vitro and in vivo, in order to provide experimental basis for the further development of paeonol into an anti-inflammatory drug in the future.

METHODS

Paeonol loaded liposomes were prepared and optimized by thin film dispersion-ultrasonic method. The absorption mechanism of paeonol-loaded liposomes was studied by pharmacokinetics, in situ single-pass intestinal perfusion and Caco-2 cell monolayer model, the anti-inflammatory activity was studied in a mouse ulcerative model.

RESULTS

Box-Behnken response surface methodology permits to screen the best formulations. The structural and morphological characterization showed that paeonol was entrapped inside the bilayer in liposomes. Pharmacokinetic studies found that the AUC_0-t of Pae-Lips was 2.78 times than that of paeonol suspension, indicating that Pae-Lips significantly improved the absorption of paeonol. In situ single intestinal perfusion and Caco-2 monolayer cell model results showed that paeonol was passively transported and absorbed, and was the substrate of P-gp, MRP2 and BCRP, and the Papp value of Pae-Lips was significantly higher than that of paeonol. In vitro and in vivo anti-inflammatory experiments showed that compared with paeonol, Pae-Lips exhibited excellent anti-inflammatory activity.

CONCLUSION

In this study, Pae-Lips were successfully prepared to improve the oral absorption of paeonol. Absorption may involve passive diffusion and efflux transporters. Moreover, Pae-Lips have excellent anti-inflammatory activity in vitro and in vivo, which preliminarily clarifies the feasibility of further development of Pae-Lips into oral anti-inflammatory drugs.

Role of Heme Oxygenase in Gastrointestinal Epithelial Cells

The gastrointestinal tract is a unique organ containing both vascular and luminal routes lined by epithelial cells forming the mucosa, which play an important role in the entry of nutrients and act as a selective barrier, excluding potentially harmful agents. Mucosal surfaces establish a selective barrier between hostile external environments and the internal milieu. Heme is a major nutritional source of iron and is a pro-oxidant that causes oxidative stress. Heme oxygenases (HOs) catalyze the rate-limiting step in heme degradation, resulting in the formation of iron, carbon monoxide, and biliverdin, which are subsequently converted to bilirubin by biliverdin reductase. In gastrointestinal pathogenesis, HO-1, an inducible isoform of HO, is markedly induced in epithelial cells and plays an important role in protecting mucosal cells. Recent studies have focused on the biological effects of the products of this enzymatic reaction, which have antioxidant, anti-inflammatory, and cytoprotective functions. In this review, the essential roles of HO in the gastrointestinal tract are summarized, focusing on nutrient absorption, protection against cellular stresses, and the maintenance and regulation of tight junction proteins, emphasizing the potential therapeutic implications. The biochemical basis of the potential therapeutic implications of glutamine for HO-1 induction in gastrointestinal injury is also discussed.

FuZhengHuaYuJiangZhuTongLuoFang Prescription Modulates Gut Microbiota and Gut-Derived Metabolites in UUO Rats

Background

Alteration of intestinal flora and metabolites is closely related to chronic kidney disease (CKD) across early to advanced stages. FuZhengHuaYuJiangZhuTongLuoFang prescription (FZHY) is a Chinese herb that has been proven to effectively treat CKD, but the underlying mechanism is not clear.

Methods

Rats were subjected to intragastric treatment with FZHY 7, 14, and 21 days after unilateral ureteral obstruction (UUO) surgery, and kidney tissue, colon tissue, serum, and stool samples were collected.

Results

FZHY treatment effectively ameliorated UUO-induced renal function loss, renal injury and renal fibrosis, and colon tissue damage and fibrosis on day 7. The results of 16S flora analysis (day 7) showed that, compared with the UUO group, both the FZHY group and the sham group showed decreased levels of g_Monoglobus, g_Papillibacter, g_Eubacterium_nodatum, and g_Family_XIII_AD3011. Additionally, FZHY obviously induced the reduction of serum citrulline, glycoursodeoxycholic acid, 23-nordeoxycholic acid, 7-ketodeoxycholic acid, kahweol, lipoid B4, 4-(3,4-dihydro-2H-1,5-benzodioxepin-7-yl)-2-methyl-1,3-thiazole, taurolithocholic acid sodium salt, indoline-2-carboxylic acid, 5(S),15(S)-diHETE, and others and the increase of bilirubin, asparagine, and others, which were positively associated with the above four candidate bacteria. Moreover, FZHY increased the levels of ZO-1, occludin, and claudin-1 in the colonic mucosa and reduced the levels of CRP, TNF-α, IL-6, and IL-1 in the serum and LN, FN, Col-I, and Col-III in the tubulointerstitium of UUO rats on day 7.

Conclusion

Our study revealed that FZHY reduced kidney damage at the early stage of CKD by regulating the above four candidate bacteria biomarkers and gut-derived harmful metabolites, inhibiting the inflammation response and tubulointerstitial fibrosis, providing deep insight into CKD therapeutic strategy.

Anti-inflammatory activities of natural cyclopeptide RA-XII in colitis-associated colon cancer mouse model and its effect on gut microbiome

Colorectal cancer (CRC), the third most common cancer globally, is associated with intestinal inflammation that leads to poor prognosis. RA-XII, a natural cyclopeptide, has previously been reported to possess anti-tumor activities. Here, the anti-inflammatory activities of RA-XII were investigated in colitis-associated colon cancer mice and a co-culture in vitro model, in which colon cancer cells HCT116 and macrophages RAW264.7 were grown together to mimic the inflammatory microenvironment of CRC. Changes of inflammatory-related molecules and protein expressions in cells were evaluated after RA-XII incubation. Besides, azoxymethane and dextran sulfate sodium-induced colitis-associated colon cancer mice were treated with RA-XII for 24 days, inflammatory parameters and gut microbiome alterations were studied. Our results showed that RA-XII reversed the inflammatory responses of RAW264.7 cells induced by LPS and modulated the protein expressions of AKT, STAT3/p-STAT3, P70S6K, NF-κB and GSK3β and suppressed the expression of LC3A/B in HCT116 cells in co-culture system. RA-XII treatment restored the colitis damage in colon, reduced colon tumors numbers and decreased inflammatory factors (IL-6, IL-10 and TNF-α). The role of RA-XII on regulating gut microbiome was also demonstrated for the first time. In conclusion, our findings provided new scientific evidence for developing RA-XII as a potent anti-inflammatory agent for CRC.

Supplementation of Dietary Quercetin and Vitamin E Promotes the Intestinal Structure and Immune Barrier Integrity in Aged Breeder Hens

In aged animals, the physiological functions of the gastrointestinal tract (GIT) are reduced. Dietary intervention is necessary to re-activate GIT functions. The objective of this study was to investigate the impacts of dietary combination of quercetin (Q) and vitamin E (VE) on the intestinal structure and barrier integrity in aged breeder chickens. A sum of 400 (65-wks-old) Tianfu breeder hens were randomly allotted into four (4) groups with four (4) replicates, and fed with basal diet; basal diet supplemented with 0.4g/kg of Q; basal diet supplemented with 0.2g/kg of VE; and basal diet supplemented with the combination of Q (0.4 g/kg) and VE (0.2 g/kg) for 14 weeks. At the end of the 14^th week, serum and gut segments were collected from eight hens per group for analyses. The results showed that Q+VE exerted synergistic effects on intestinal morphology by promoting villi height and crypt depth (P < 0.05), as well as mitigated the intestinal inflammatory damage of the aged hens, but decreased the concentration of serum D-lactate and diamine oxidase; and increased the levels of secretory immunoglobulin A (sIgA) and Mucin-2 mRNA (P < 0.05). Furthermore, the mRNA expression of intestinal tight junction proteins including occludin, ZO1, and claudin-1 was increased by Q+VE (P < 0.05). Moreover, Q+VE decreased the mRNA expression of the pro-inflammatory genes (TNF-α, IL-6, and IL-1β), and increased the expression of anti-inflammatory genes (IL-10 and IL-4) (P < 0.05). These results were consistent with the mRNA expression of Bax and Bcl-2. In addition, Q+VE protected the small intestinal tract from oxidative damage by increasing the levels of superoxide dismutase, total antioxidant capacity, glutathione peroxidase, catalase (P < 0.05), and the mRNA expression of SOD1 and GPx-2. However, Q+VE decreased malondialdehyde levels in the intestine compared to the control (P < 0.05). These results indicated that dietary Q+VE improved intestinal function in aged breeder hens, by protecting the intestinal structure and integrity. Therefore, Q+VE could act as an anti-aging agent to elevate the physiological functions of the small intestine in chickens.

Maternal disease factors associated with neonatal jaundice: a case-control study

Background

Neonatal jaundice is common, and despite the considerable medical costs associated with it, there are still few studies on the maternal factors associated with it. Identification of maternal factors associated with neonatal jaundice is very important in terms of prevention, screening and management of neonatal jaundice. The current study aimed to identify maternal disease factors associated with neonatal jaundice.

Methods

We compared the maternal disease diagnostic codes during pregnancy (study A) and 1 year before conception (study B) in mothers whose insurance claims data included newborns treated for neonatal jaundice before birth registration via the National Health Insurance Service–National Sample Cohort (control group). To decrease the effect of confounding variables, the neonatal jaundice and control groups were matched at a ratio of 1:10 via propensity score matching using covariates including age and income.

Results

The matched samples for studies A and B included 4,026 and 3,278 (jaundice group: 366 and 298) delivery cases, respectively. In both studies, the jaundice group had a higher proportion of patients who underwent cesarean section than the control group. In study A, other diseases of the digestive system had the highest odds ratio (OR) (K92; adjusted OR: 14.12, 95% confidence interval [CI]: 2.70–82.26). Meanwhile, gastritis and duodenitis had the lowest OR (K29; adjusted OR: 0.39, 95% CI: 0.22–0.69). In study B, salpingitis and oophoritis had the highest OR (N70; adjusted OR: 3.33, 95% CI: 1.59–6.94). Heartburn had the lowest OR (R12; adjusted OR: 0.29, 95% CI:0.12–0.71).

Conclusions

This study identified maternal disease factors correlated with neonatal jaundice during pregnancy and 1 year before conception. Maternal risk factors for neonatal jaundice included syphilis and leiomyoma during pregnancy, and salpingo-oophoritis before pregnancy. The protective factors included infection, inflammatory diseases, and dyspepsia.

Bacillus toyonensis SAU-19 and SAU-20 Isolated From Ageratina adenophora Alleviates the Intestinal Structure and Integrity Damage Associated With Gut Dysbiosis in Mice Fed High Fat Diet

This study was performed to identify potential probiotic endophytes from Ageratina adenophora and evaluate their ameliorating effects on gut injury and integrity damage associated with microbiota dysbiosis in mice fed high fat diet. Using morphological and biochemical tests, and 16S rRNA gene sequencing technique, two bacteria endophytes were identified as strains of Bacillus toyonensis and were named Bacillus toyonensis SAU-19 (GenBank No. MW287198) and Bacillus toyonensis SAU-20 (GenBank No. MW287199). Sixty (60) mice were divided into five groups, group 1 was the negative control fed normal diet (NS), group 2 was fed High fat diet (HF), Group 3 was fed High fat diet + 106 Lactobacillus rhamnosus (LGG), group 4 was fed High fat + 106 Bacillus toyonensis SAU-19 and group 5 fed High fat diet + 106 Bacillus toyonensis SAU-20. After 35 days, histological and immunohistochemistry examination were performed in the ileum tissues. Furthermore, DAO and antioxidants activities were measured in serum, mRNA expressions of tight junction proteins (occludin and ZO-1) and inflammation related cytokines (IL-1β, TFN-α, IL-2, IL-4, and IL-10) in the ileum tissues as well as sIgA levels and total bacteria (Escherichia coli, Salmonella, Staphylococcus, and Lactobacillus) in the small intestine and cecum content. The results showed an increase in the DAO activity, oxidative stress parameter (MDA), pro-inflammation cytokines (IL-1β, TFN-α, IL-2), reduce immunity (sIgA), and destroyed intestinal structure and integrity (reduce tight junction proteins) in the high fat diet group and this was associated with destruction of the gut microbiota composition (increasing pathogenic bacteria; E. coli, Salmonella, Staphylococcus and reducing beneficial bacteria, Lactobacillus spp.) in mice (P < 0.05). However, the administration of Bacillus toyonensis SAU-19 and SAU-20 reverted these effects. Our findings indicated that, Bacillus toyonensis SAU-19 and SAU-20 isolated from A. adenophora could prevent the excess weight gain from high fat diet feeding, improved antioxidant status and alleviated the intestine integrity damage as well as reduce the population of enteric bacteria such as E. coli, Salmonella, and S. aureus and increasing the population of beneficial bacteria such as Lactobacillus in the gut of mice fed high fat diet, therefore, can serve as a potential probiotics in humans and animals.

Identifying Potential Therapeutic Applications and Diagnostic Harms of Increased Bilirubin Concentrations: A Clinical and Genetic Approach

Bilirubin has antioxidant and anti-inflammatory properties in vitro and in animal studies and protects against inflammatory, cardiovascular, and other diseases in observational studies; therefore, bilirubin has potential as a therapeutic agent. However, observational studies could be confounded by many factors. We used a genetic (n = 61,281) and clinical (n = 234,670) approach to define the association between bilirubin and 19 conditions with a putative protective signal in observational studies. We also tested if individuals with genetically higher bilirubin levels underwent more diagnostic tests. We used a common variant in UGT1A1 (rs6742078) associated with an 26% increase in bilirubin levels in the genetic studies. Carriers of the variant had higher bilirubin levels (P = 2.2 × 10-16 ) but there was no significant association with any of the 19 conditions. In a phenome-wide association study (pheWAS) to seek undiscovered genetic associations, the only significant finding was increased risk of "jaundice-not of newborn." Carriers of the variant allele were more likely to undergo an abdominal ultrasound (odds ratio = 1.04, [1.00-1.08], P = 0.03). In contrast, clinically measured bilirubin levels were significantly associated with 15 of the 19 conditions (P < 0.003) and with 431 clinical diagnoses in the pheWAS (P < 1 × 10-5 adjusted for sex, age, and follow-up). With additional adjustment for smoking and body mass index, 7 of 19 conditions and 260 pheWAS diagnoses remained significantly associated with bilirubin levels. In conclusion, bilirubin does not protect against inflammatory or other diseases using a genetic approach; the many putative beneficial associations reported clinically are likely due to confounding.

Sucralose enhances the susceptibility to dextran sulfate sodium (DSS) induced colitis in mice with changes in gut microbiota

Sucralose is one of the most widely used artificial sweeteners, free of nutrients and calories. Its approval and uses correlate with many of the worldwide epidemiological changes in inflammatory bowel disease (IBD). Multiple animal studies by us and others showed that sucralose exacerbated ileitis in SAMP1/YitFc mice and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. In this study, we further investigated the effect of sucralose on dextran sulfate sodium (DSS)-induced colitis in mice and the associated mechanisms. Male C57BL/6 mice received 1.5 mg ml^-1 sucralose in drinking water for 6 weeks. Then, 2.5% DSS was added to drinking water for 7 days to induce ulcerative colitis (UC). The results showed that, compared with the DSS group, administration of sucralose exacerbated the severity of colitis as indicated by the further decrease in body weight, increase in disease activity index (DAI) and the expression of pro-inflammatory cytokines, as well as the activation of the TLR5-MyD88-NF-κB signaling pathway, and the disturbances of intestinal barrier function, along with changes in the intestinal microbiota. Our findings indicate that sucralose may increase the susceptibility to DSS-induced colitis through causing dysbiosis of intestinal microbiota and damage to the intestinal barrier.

The Protective Role of the Heme Catabolic Pathway in Hepatic Disorders

Significance: As the central metabolic organ, the liver is exposed to a variety of potentially cytotoxic, proinflammatory, profibrotic, and carcinogenic stimuli. To protect the organism from these deleterious effects, the liver has evolved a number of defense systems, which include antioxidant substrates and enzymes, anti-inflammatory tools, enzymatic biotransformation systems, and metabolic pathways. Recent Advances: One of the pivotal systems that evolved during phylogenesis was the heme catabolic pathway. Comprising the important enzymes heme oxygenase and biliverdin reductase, this complex pathway has a number of key functions including enzymatic activities, but also cell signaling, and DNA transcription. It further generates two important bile pigments, biliverdin and bilirubin, as well as the gaseous molecule carbon monoxide. These heme degradation products have potent antioxidant, immunosuppressive, and cytoprotective effects. Recent data suggest that the pathway participates in the regulation of metabolic and hormonal processes implicated in the pathogenesis of hepatic and other diseases. Critical Issues: This review discusses the impact of the heme catabolic pathway on major liver diseases, with particular focus on the involvement of cellular targeting and signaling in the pathogenesis of these conditions. Future Directions: To utilize the biological consequences of the heme catabolic pathway, several unique therapeutic strategies have been developed. Research indicates that pharmaceutical, nutraceutical, and lifestyle modifications positively affect the pathway, delivering potentially long-term clinical benefits. However, further well-designed studies are needed to confirm the clinical benefits of these approaches. Antioxid. Redox Signal. 35, 734-752.

Ageratina adenophora Disrupts the Intestinal Structure and Immune Barrier Integrity in Rats

The aim of this study was to investigate the effects of Ageratina adenophora on the intestines morphology and integrity in rat. Rats were randomly divided into two groups and were fed with 10 g/100 g body weight (BW) basal diet and 10 g/100 g BW experimental diet, which was a mixture of A. adenophora powder and basal diet in a 3:7 ratio. The feeding experiment lasted for 60 days. At days 28 and 60 of the experiment, eight rats/group/timepoint were randomly selected, weighed, and sacrificed, then blood and intestinal tissues were collected and stored for further analysis. The results showed that Ageratina adenophora caused pathological changes and injury in the intestine, elevated serum diamine oxidase (DAO), D-lactate (D-LA), and secretory immunoglobulin A (sIgA) levels, reduced occludin levels in intestinal tissues, as well as increased the count of intraepithelial leukocytes (IELs) and lamina propria leukocytes (LPLs) in the intestine (p < 0.05 or p < 0.01). In addition, the mRNA and protein (ELISA) expressions of pro-inflammation cytokines (IL-1β, IL-2, TNF-α, and IFN-ϒ) were elevated in the Ageratina adenophora treatment groups, whereas anti-inflammatory cytokines such as IL-4 and IL-10 were reduced (p < 0.01 or p < 0.05). Therefore, the results obtained in this study indicated that Ageratina adenophora impaired intestinal function in rats by damaging the intestine structure and integrity, and also triggered an inflammation immune response that led to intestinal immune barrier dysfunction.

A case-control study on the association of intestinal flora with ulcerative colitis

The association between intestinal flora and ulcerative colitis (UC) was studied in order to provide a basis and method for clinical treatment. Fresh fecal samples were collected from 30 active UC patients and 10 healthy controls. The intestinal flora DNA from each sample was extracted and 16S rRNA gene sequencing was carried out using HiSeq platform to identify the intestinal flora in fecal samples. The richness and diversity of intestinal flora in UC patients were significantly lower than those in healthy control group (P < 0.05). Significant differences were observed between the intestinal flora-species of UC patients and healthy controls. Synergistetes (P < 0.01) and Firmicutes (P < 0.05), along with probiotics Veillonella (P < 0.01), Ruminococcus and Coprococcus (P < 0.05) in the UC patients were lower than that in the healthy controls significantly. Furthermore, compared with the control group, Tenericutes (P < 0.01) and intestinal pathogenic bacteria, including Bacteroides (P < 0.01), Escherichia and Sutterella (P < 0.05) were significantly increased. The incidence of UC is significantly associated with the changes in intestinal flora. Changes in intestinal flora may lead to a decrease in the diversity of intestinal flora or to the enrichment of a particular intestinal flora.

Regulation of inflammation by the antioxidant haem oxygenase 1

Haem oxygenase 1 (HO-1), an inducible enzyme responsible for the breakdown of haem, is primarily considered an antioxidant, and has long been overlooked by immunologists. However, research over the past two decades in particular has demonstrated that HO-1 also exhibits numerous anti-inflammatory properties. These emerging immunomodulatory functions have made HO-1 an appealing target for treatment of diseases characterized by high levels of chronic inflammation. In this Review, we present an introduction to HO-1 for immunologists, including an overview of its roles in iron metabolism and antioxidant defence, and the factors which regulate its expression. We discuss the impact of HO-1 induction in specific immune cell populations and provide new insights into the immunomodulation that accompanies haem catabolism, including its relationship to immunometabolism. Furthermore, we highlight the therapeutic potential of HO-1 induction to treat chronic inflammatory and autoimmune diseases, and the issues faced when trying to translate such therapies to the clinic. Finally, we examine a number of alternative, safer strategies that are under investigation to harness the therapeutic potential of HO-1, including the use of phytochemicals, novel HO-1 inducers and carbon monoxide-based therapies.

Can bilirubin nanomedicine become a hope for the management of COVID-19?

Bilirubin has been proven to possess significant anti-inflammatory, antioxidant and antiviral activities. Recently, it has been postulated as a metabolic hormone. Further, moderately higher levels of bilirubin are positively associated with reduced risk of cardiovascular diseases, diabetes, metabolic syndrome and obesity. However, due to poor solubility the therapeutic delivery of bilirubin remains a challenge. Nanotechnology offers unique advantages which may be exploited for improved delivery of bilirubin to the target organ with reduced risk of systemic toxicity. Herein, we postulate the use of intravenous administration or inhalational delivery of bilirubin nanomedicine (BNM) to combat systemic dysfunctions associated with COVID-19, owing to the remarkable preclinical efficacy and optimistic results of various clinical studies of bilirubin in non-communicable disorders. BNM may be used to harness the proven preclinical pharmacological efficacy of bilirubin against COVID-19 related systemic complications.

Association between serum bilirubin and mucosal healing among Japanese patients with ulcerative colitis: a cross-sectional study

PURPOSE

Bilirubin is known to have antioxidant effects. Several pieces of evidence regarding association between serum bilirubin and UC exist. Three studies found that serum bilirubin was inversely associated with severity of ulcerative colitis (UC), but no evidence regarding an association between serum bilirubin and mucosal healing (MH) has yet been shown. Thus, we evaluated this issue among Japanese patients with UC.

METHODS

The study subjects consisted of 304 Japanese patients with UC. Serum total bilirubin and indirect bilirubin were divided into quartiles on the basis of the distribution of all study subjects (low, moderate, high, and very high). Several endoscope specialists were responsible for evaluating MH, which was defined as a Mayo endoscopic subscore of 0. The information on clinical remission was collected using medical records.

RESULTS

The mean age was 49.9 years, the percentage of male patients was 59.2%, and the percentage of MH was 29.3%. High serum total bilirubin was independently positively associated with MH (OR 2.26 [95%CI 1.13-4.61]. However, after adjustment for confounding factors, the association between total bilirubin and MH disappeared. Very high serum indirect bilirubin was independently positively associated with MH (OR 2.31 [95%CI 1.10-5.00], p for trend = 0.026). No association between bilirubin and clinical remission was found.

CONCLUSIONS

Among Japanese patients with UC, serum indirect bilirubin, but not total bilirubin, was significantly positively associated with MH but not clinical remission.

Bilirubin Nanoparticles Reduce Diet-Induced Hepatic Steatosis, Improve Fat Utilization, and Increase Plasma β-Hydroxybutyrate

The inverse relationship of plasma bilirubin levels with liver fat accumulation has prompted the possibility of bilirubin as a therapeutic for non-alcoholic fatty liver disease. Here, we used diet-induced obese mice with non-alcoholic fatty liver disease treated with pegylated bilirubin (bilirubin nanoparticles) or vehicle control to determine the impact on hepatic lipid accumulation. The bilirubin nanoparticles significantly reduced hepatic fat, triglyceride accumulation, de novo lipogenesis, and serum levels of liver dysfunction marker aspartate transaminase and ApoB100 containing very-low-density lipoprotein. The bilirubin nanoparticles improved liver function and activated the hepatic β-oxidation pathway by increasing PPARα and acyl-coenzyme A oxidase 1. The bilirubin nanoparticles also significantly elevated plasma levels of the ketone β-hydroxybutyrate and lowered liver fat accumulation. This study demonstrates that bilirubin nanoparticles induce hepatic fat utilization, raise plasma ketones, and reduce hepatic steatosis, opening new therapeutic avenues for NAFLD.

Heme Oxygenase-1 in Gastrointestinal Tract Health and Disease

Heme oxygenase 1 (HO-1) is the rate-limiting enzyme of heme oxidative degradation, generating carbon monoxide (CO), free iron, and biliverdin. HO-1, a stress inducible enzyme, is considered as an anti-oxidative and cytoprotective agent. As many studies suggest, HO-1 is highly expressed in the gastrointestinal tract where it is involved in the response to inflammatory processes, which may lead to several diseases such as pancreatitis, diabetes, fatty liver disease, inflammatory bowel disease, and cancer. In this review, we highlight the pivotal role of HO-1 and its downstream effectors in the development of disorders and their beneficial effects on the maintenance of the gastrointestinal tract health. We also examine clinical trials involving the therapeutic targets derived from HO-1 system for the most common diseases of the digestive system.

Perspective: Prospects for Nutraceutical Support of Intestinal Barrier Function

Impairment of intestinal barrier function is linked to certain pathologies and to aging, and can be a cause of bacterial infections, systemic and hepatic inflammation, food allergies, and autoimmune disorders. The formation and maintenance of intestinal tight junctions is supported by glucagon-like peptide-2 (GLP-2), which via insulin-like growth factor I activity boosts phosphoinositide 3-kinase/Akt/mammalian target of rapamycin complex 1 (PI3K/Akt/mTORC1) signaling in enterocytes. 5'-AMP-activated protein kinase (AMPK) activity as well as estrogen receptor-β (ERβ) activity are also protective in this regard. Conversely, activation of mitogen-activated protein kinases (MAPKs) and cellular Src (c-Src) under inflammatory conditions can induce dissociation of tight junctions. Hence, nutraceuticals that promote GLP-2 secretion from L cells-effective pre/probiotics, glycine, and glutamine-as well as diets rich in soluble fiber or resistant starch, can support intestinal barrier function. AMPK activators-notably berberine and the butyric acid produced by health-promoting microflora-are also beneficial in this regard, as are soy isoflavones, which function as selective agonists for ERβ. The adverse impact of MAPK and c-Src overactivation on the intestinal barrier can be combatted with various antioxidant measures, including phycocyanobilin, phase 2-inducer nutraceuticals, and N-acetylcysteine. These considerations suggest that rationally designed functional foods or complex supplementation programs could have clinical potential for supporting and restoring healthful intestinal barrier function.

The Role of HIF in Immunity and Inflammation

HIF is a transcription factor that plays an essential role in the cellular response to low oxygen, orchestrating a metabolic switch that allows cells to survive in this environment. In immunity, infected and inflamed tissues are often hypoxic, and HIF helps immune cells adapt. HIF-α stabilization can also occur under normoxia during immunity and inflammation, where it regulates metabolism but in addition can directly regulate expression of immune genes. Here we review the role of HIF in immunity, including its role in macrophages, dendritic cells, neutrophils, T cells, and B cells. Its role in immunity is as essential for cellular responses as it is in its original role in hypoxia, with HIF being implicated in multiple inflammatory diseases and in immunosuppression in tumors.

Two Faces of Heme Catabolic Pathway in Newborns: A Potential Role of Bilirubin and Carbon Monoxide in Neonatal Inflammatory Diseases

In an infant's body, all the systems undergo significant changes in order to adapt to the new, extrauterine environment and challenges which it poses. Fragile homeostasis can be easily disrupted as the defensive mechanisms are yet imperfect. The activity of antioxidant enzymes, i.e., superoxide dismutase, catalase, and glutathione peroxidase, is low; therefore, neonates are especially vulnerable to oxidative stress. Free radical burden significantly contributes to neonatal illnesses such as sepsis, retinopathy of premature, necrotizing enterocolitis, bronchopulmonary dysplasia, or leukomalacia. However, newborns have an important ally-an inducible heme oxygenase-1 (HO-1) which expression rises rapidly in response to stress stimuli. HO-1 activity leads to production of carbon monoxide (CO), free iron ion, and biliverdin; the latter is promptly reduced to bilirubin. Although CO and bilirubin used to be considered noxious by-products, new interesting properties of those compounds are being revealed. Bilirubin proved to be an efficient free radicals scavenger and modulator of immune responses. CO affects a vast range of processes such as vasodilatation, platelet aggregation, and inflammatory reactions. Recently, developed nanoparticles consisting of PEGylated bilirubin as well as several kinds of molecules releasing CO have been successfully tested on animal models of inflammatory diseases. This paper focuses on the role of heme metabolites and their potential utility in prevention and treatment of neonatal diseases.

Pingkui Enema Alleviates TNBS-Induced Ulcerative Colitis by Regulation of Inflammatory Factors, Gut Bifidobacterium, and Intestinal Mucosal Barrier in Rats

Background

Ulcerative colitis (UC) is a chronic recurrent inflammation of the colon, and clinical outcome of UC is still unsatisfied. Pingkui enema, a traditional Chinese medicine prescription, has been safely applied for the treatment of diarrhea and dysentery in clinic for many years. However, its mechanism is still elusive. The present study is designed to investigate the effect of Pingkui enema on trinitrobenzene sulfonic acid- (TNBS-) induced ulcerative colitis (UC) and possible mechanism in rats.

Methods

UC was induced by intracolonic instillation of TNBS in male Sprague-Dawley rats, which were treated with different dosages of Pingkui enema (low, medium, and high) or sulfasalazine for ten days. Survival rate was calculated. A clinical disease activity score was evaluated. Histological colitis severity was analyzed by hematoxylin-eosin (HE) staining. Content of Bifidobacterium in intestinal tissue was analyzed by RT-PCR. Concentration of IL-8, IL-13, TNF-α, D-lactic acid (D-LA), and diamine oxidase (DAO) in serum and contents of adhesin and receptor of Bifidobacterium adhesion in rat intestinal mucus were measured by ELISA.

Results

The results showed that Pingkui enema treatment with high dosage markedly improved the survival rate compared with untreated and sulfasalazine treated groups. All dosages of Pingkui enema reduced pathological score. High dosage of Pingkui enema and sulfasalazine treatments significantly reduced the serum concentration of IL-8, TNF-α, D-LA, and DAO and markedly increased the serum concentration of IL-13. In addition, high-dose Pingkui enema and sulfasalazine treatments increased gut content of Bifidobacterium, gut mucus expressions of adhesin, and adhesin receptor of Bifidobacterium.

Conclusions

Pingkui enema has therapeutic effect on TNBS-induced UC, and possible mechanism may be via regulation of gut probiotics (Bifidobacterium) and inflammatory factors and protection of intestinal mucosal barrier.

Mutual regulation between butyrate and hypoxia-inducible factor-1α in epithelial cell promotes expression of tight junction proteins

Inflammatory bowel disease is a kind of multi-aetiological chronic disease that is driven by multidimensional factors. Hypoxia-inducible factor-1α (HIF-1α) plays an important role in anti-inflammatory and cellular responses to hypoxia. Previous studies have found that B or T-cell-specific HIF-1α knock out mice exhibit severe colonic inflammation. However, we know very little about other functions of HIF-1α in intestinal epithelial cells (IECs). In our study, HIF-1α^ΔIEC mice were used to study the function of HIF-1α in IECs. HIF-1α was knocked down in Caco-2 cells by transfection with a small interfering (si) RNA. Immunohistochemical staining and western blotting were used to detect the expression of zonula occluden-1 (ZO-1) and Occludin. The content of colon was harvested for high-performance liquid chromatography analysis to examine the levels of butyrate in the gut. Our research found that HIF-1α played a protective role in dextran sulphate sodium-induced colitis, which was partly due to its regulation of tight junction (TJ) protein expression. Further study revealed that HIF-1α mediated TJ proteins levels by moderating the content of butyrate. Moreover, we found that butyrate regulated TJ protein expression, which is dependent on HIF-1α. These results indicated that there is a mutual regulatory mechanism between butyrate and HIF-1α, which has an important role in the maintenance of barrier function of the gastrointestinal tract.

Bilirubin Safeguards Cardiorenal and Metabolic Diseases: a Protective Role in Health

PURPOSE OF REVIEW

To discuss recent advances indicating that bilirubin safeguards against cardiorenal and metabolic diseases.

RECENT FINDINGS

Several investigations from human patient populations and experimental animal models have shown that bilirubin improves cardiorenal and metabolic dysfunction. The latest studies found an entirely new function of bilirubin suggesting that it acts as a hormone signaling molecule capable of activating nuclear receptors for burning fat, which may explain several of its protective actions. This review highlights the current findings (within the last 3 years) regarding cardiorenal and metabolic protective effects of bilirubin and the latest mechanism(s) that may be mediating these effects.

Heme Catabolic Pathway in Inflammation and Immune Disorders

In recent years, the heme catabolic pathway is considered to play an important regulatory role in cell protection, apoptosis, inflammation, and other physiological and pathological processes. An appropriate amount of heme forms the basic elements of various life activities, while when released in large quantities, it can induce toxicity by mediating oxidative stress and inflammation. Heme oxygenase (HO) -1 can catabolize free heme into carbon monoxide (CO), ferrous iron, and biliverdin (BV)/bilirubin (BR). The diverse functions of these metabolites in immune systems are fascinating. Decades work shows that administration of degradation products of heme such as CO and BV/BR exerts protective activities in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS) and other immune disorders. This review elaborates the molecular and biochemical characterization of heme catabolic pathway, discusses the signal transduction and immunomodulatory mechanism in inflammation and summarizes the promising therapeutic strategies based on this pathway in inflammatory and immune disorders.