Elevated systemic zonula occludens 1 is positively correlated with inflammation in cirrhosis

Findings on the Relationship Between Intestinal Microbiome and Vasculitis

The microbiome has been implicated in small-, medium-, large-, and variable-vessel vasculitis. Dysbiosis can frequently be found in vasculitis patients with altered microbial diversity and abundance, compared with those with other diseases and healthy controls. Dominant bacteria discovered in different studies vary greatly, but in general, the intestinal microbiome in vasculitis patients tends to contain more pathogenic and less beneficial bacteria. Improvement or resolution of dysbiosis has been observed after treatment in a few longitudinal studies. In addition, some molecular changes in intestinal permeability and immune response have been found in animal models of vasculitis diseases.

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.

Tight junction protein ZO-1 in Kawasaki disease

Background

Kawasaki disease (KD) is a form of systemic febrile vasculitis that is complicated with coronary artery lesions (CAL). The tight junctions that maintain the intestinal barrier also play a role in systemic inflammatory diseases. Serum zonula occludens-1 (ZO-1) expression was found to be significantly lower in asthmatic patients, and another study reported that elevated systemic ZO-1 was positively correlated with inflammation in cirrhotic patients. A murine model of KD vasculitis demonstrated that vasculitis depended on intestinal barrier dysfunction, which is maintained by tight junctions. In this study, we aimed to investigate the role of the tight junction zonula occludens-1 (ZO-1) in the treatment response of intravenous immunoglobulin (IVIG) and the occurrence of CAL formation in KD patients.

Methods

We enrolled 40 KD patients, 12 healthy controls, and 12 febrile controls in this study. The serum levels of tight junction ZO-1 were determined by enzyme-linked immunosorbent assay.

Results

The serum ZO-1 level was higher in the fever control group but did not reach a statistical significance. KD patients who received a second dose of IVIG treatment due to initial IVIG unresponsiveness had a higher serum levels of tight junction ZO-1, but without statistical significance (2.15 ± 0.18 vs. 2.69 ± 0.31 ng/mL, p = 0.058). KD patients who developed a CAL demonstrated a significant lower serum tight junction ZO-1 levels than KD without CAL formation (1.89 ± 0.16 vs. 2.39 ± 0.15 ng/mL, p = 0.027). After multiple logistic regression analysis, ZO-1 levels [(95% confidence interval (CI): 0.058 ~ 0.941, odds ratio (OR) = 0.235, p = 0.041)] showed as the risk factor for CAL formation.

Conclusion

Serum levels of tight junction ZO-1 levels were lower in KD patients than fever controls and associated with CAL formation.

Elevated levels of circulating short-chain fatty acids and bile acids in type 2 diabetes are linked to gut barrier disruption and disordered gut microbiota

AIMS

Studies have shown that destruction of the intestinal barrier in type 2 diabetes (T2D) leads to increased absorption of macromolecules from intestinal. We previously exhibited that short-chain fatty acids (SCFAs) and bile acids (BAs) were significantly decreased in faeces of T2D patients. In the current study, we extended these findings by focusing on the interactions between intestinal barrier and clinical characteristics, gut microbiota, SCFAs and BAs.

METHODS

65 T2D patients and 35 healthy controls were recruited, targeted metabolomics was used to evaluate the SCFAs and BAs in their serum samples. The serum zonula occludens-1 (ZO-1) was measured by ELISA to evaluate intestinal barrier.

RESULTS

Compared with the healthy controls, the serum concentrations of total SCFA, acetate and propionate were significantly increased in the T2D patients, and certain BAs were also significantly increased. In addition, the higher levels of serum ZO-1 suggested a "leaky gut" in T2D patients. The ZO-1 was comprehensively correlated with clinical characteristics, gut microbiota, SCFAs and BAs.

CONCLUSION

SCFAs and BAs were excessively absorbed from the intestinal through the leaky gut, leading to higher levels of circulating SCFAs and BAs in T2D patients, and that the leaky gut might be caused by the disordered gut microbiota.

Overview of the Assessment of Endothelial Function in Humans

The endothelium is recognized to play an important role in various physiological functions including vascular tone, permeability, anticoagulation, and angiogenesis. Endothelial dysfunction is increasingly recognized to contribute to pathophysiology of many disease states, and depending on the disease stimuli, mechanisms underlying the endothelial dysfunction may be markedly different. As such, numerous techniques to measure different aspects of endothelial dysfunction have been developed and refined as available technology improves. Current available reviews on quantifying endothelial dysfunction generally concentrate on a single aspect of endothelial function, although diseases may affect more than one aspect of endothelial function. Here, we aim to provide an overview on the techniques available for the assessment of the different aspects of endothelial function in humans, human tissues or cells, namely vascular tone modulation, permeability, anticoagulation and fibrinolysis, and the use of endothelial biomarkers as predictors of outcomes.

Probiotic Bacillus Spores Protect Against Acetaminophen Induced Acute Liver Injury in Rats

Acetaminophen (APAP) is one of the most used analgesics and antipyretic agents in the world. Intoxication with APAP is the main cause of acute liver toxicity in both the US and Europe. Spore-forming probiotic bacteria have the ability to resist harsh gastric and intestinal conditions. The aim of this study was to investigate the possible protective effect of Bacillus (B) species (sp) spores (B. licheniformis, B. indicus, B. subtilis, B. clausii, B. coagulans) against hepatotoxicity induced by APAP in rats. A total of 35 rats were randomly divided into seven groups: group I served as control; group II received silymarin; group III received MegaSporeBiotic^TM (MSB); group IV received APAP and served as the model of hepatotoxicity; group V received APAP and silymarin; group VI received APAP and MSB; group VII received APAP, silymarin and MSB. The livers for histopathological examination and blood samples were collected on the last day of the experiment. We determined aspartate aminotransferase (AST), alanine aminotransferase (ALT) and total antioxidant capacity (TAC) levels and zonula occludens (ZO-1), tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) expression. APAP overdose increased AST and ALT. It slowly decreased TAC compared to the control group, but pretreatment with silymarin and MSB increased TAC levels. Elevated plasma concentrations were identified for ZO-1 in groups treated with APAP overdose compared with those without APAP or receiving APAP in combination with silymarin, MSB or both. The changes were positively correlated with the levels of other proinflammatory cytokines (TNF-α, IL-1β). In addition, histopathological hepatic injury was improved by preadministration of MSB or silymarin versus the disease model group. Bacillus sp spores had a protective effect on acute hepatic injury induced by APAP. Pretreatment with MSB resulted in a significant reduction in serum AST, ALT, TNF-α, IL-1β, ZO-1, TAC and also hepatocyte necrosis, similar to the well-known hepatoprotective agent—silymarin.

Pregnane X receptor activation by its natural ligand Ginkgolide-A improves tight junction proteins expression and attenuates bacterial translocation in cirrhosis

BACKGROUND AND AIMS

Pregnane X receptor (PXR) is a ligand-activated transcription factor and nuclear receptor expressed ubiquitously along gut-liver-axis. Inflammatory bowel disorders have been reported to implicate PXR in maintaining tight junction (TJ) integrity and countering inflammation. However, the hepatoprotective role of PXR activation in soothing bacterial translocation in liver cirrhosis has not been explored. Ginkgolide A (GA), a terpene trilactone from Ginkgo Biloba extract, is a natural ligand of rodent and human PXR. This study aims to investigate the effect of GA in activating PXR and improving associated tight junction integrity and reducing bacterial translocation in gut-liver axis of CCl₄ induced cirrhosis model.

METHODS

Swiss albino mice were administered with CCl₄ (0.5 ml/kg body weight, i.p) in corn oil for 12 weeks at an interval of two times a week. Following ascites induction, mice were randomized & administered 100 mg/kg body weight of GA through oral gavage for 2 weeks. At termination, blood, gut and liver tissues were collected for biochemical and molecular studies.

RESULTS

When compared to naïve mice, protein expression of hepatic and small intestinal PXR, CYP3A, ZO-1 and occludin were found to be significantly (p < 0.01) decreased in CCl₄ induced cirrhotic mice. Treatment with GA to cirrhotic mice significantly (p < 0.05) induced the expression of both hepatic and small intestinal PXR, CYP3A, ZO-1 and Occludin. Furthermore, increased (p < 0.01) hepatic and small intestinal NFκB was observed in CCl₄ induced cirrhotic mice that was significantly (p < 0.05) lowered following GA treatment. Over expression of TLR4/MyD88/NFκB axis and its downstream pro-inflammatory mediators TNF-α, IL6 and IFN-γ were observed in CCl₄ induced mice, and these indices were abrogated significantly after GA treatment. Furthermore, significantly increased plasma levels of bacterial translocation markers LBP and procalcitonin were found in CCl₄ mice, which were reduced significantly (p < 0.05 & p < 0.0001) after GA treatment.

CONCLUSION

In conclusion, our data supports the hypothesis that, GA treatment to CCl₄ induced cirrhotic mice, activated hepatic and small intestinal PXR and diminished inflammation, thereby improving tight junction integrity and attenuating bacterial translocation.

Risk factors associated with intestinal permeability in an adult population: A systematic review

BACKGROUND

Increased intestinal permeability (IP) involves the loss of integrity between the cells of the small intestine. IP has been suggested to contribute to the pathogenesis and exacerbation of many chronic diseases. Many potential risk factors for IP are proposed in contemporary literature. The purpose of this review is to identify the most significant risk factors for IP.

METHODS

A systematic search of literature published up until September 2018 in the PubMed, EMBASE, CINAHL, and Scopus databases was conducted.

RESULTS

A total of 47 articles met the inclusion criteria. Elevated levels of proinflammatory markers, dyslipidaemia, hyperglycaemia, insulin resistance, anthropometric measurements resembling obesity, advanced disease severity, comorbidity and the consumption of a Western-style diet were identified as the strongest risk factors for altered intestinal integrity. The risk of IP increases when coupled with a multiple disease state or combined with other environmental risk factors. Furthermore, many of the identified risk factors such as anthropometric measurements and biomarkers were external from intestinal health and rather resembled a metabolic-like condition.

CONCLUSIONS

This review identified a number of potential risk factors for IP, ranging from biomarkers to anthropometric measurements, demographics, dietary intake and chronic diseases. These risk factors warrant the attention of clinicians and other healthcare providers to aid the identification of potential patients at risk of altered IP. Further research needs to examine whether the identified risk factors are homogeneous with the diagnosis of IP or whether the disease state influences the association.

Dietary approach and gut microbiota modulation for chronic hepatic encephalopathy in cirrhosis

Hepatic encephalopathy (HE) is a common and serious neuropsychiatric complication of cirrhosis, acute liver failure, and porto-systemic shunting. HE largely contributes to the morbidity of patients with liver disease, severely affecting the quality of life of both patients and their relatives and being associated with poor prognosis. Its presentation is largely variable, manifesting with a broad spectrum of cognitive abnormalities ranging from subtle cognitive impairment to coma. The pathogenesis of HE is complex and has historically been linked with hyperammonemia. However, in the last years, it has become evident that the interplay of multiple actors, such as intestinal dysbiosis, gut hyperpermeability, and neuroinflammation, is of crucial importance in its genesis. Therefore, HE can be considered a result of a dysregulated gut-liver-brain axis function, where cognitive impairment can be reversed or prevented by the beneficial effects induced by "gut-centric" therapies, such as non-absorbable disaccharides, non-absorbable antibiotics, probiotics, prebiotics, and fecal microbiota transplantation. In this context dietary modifications, by modulating the intestinal milieu, can also provide significant benefit to cirrhotic patients with HE. This review will provide a comprehensive insight into the mechanisms responsible for gut-liver-brain axis dysregulation leading to HE in cirrhosis. Furthermore, it will explore the currently available therapies and the most promising future treatments for the management of patients with HE, with a special focus on the dietary approach.

Bacterial translocation in patients with liver cirrhosis: physiology, clinical consequences, and practical implications

The gut liver axis is an operative unit that works to protect the human body against potentially harmful substances and microorganisms, maintaining the homeostasis of the immune system. Liver cirrhosis profoundly alters this complex system. The intestine becomes more permeable allowing the translocation of bacteria, bacterial products and fragments into the portal circulation, triggering an abnormal local and systemic inflammatory response and a condition of perpetual immunologic alarm. This immune-inflammatory disorder related to dysbiosis is involved in the development of liver damage and liver cirrhosis complications and increases intestinal permeability in a vicious circle. Areas covered: The most relevant studies on bacterial translocation, the mechanism of intestinal barrier dysfunction and its consequences in patients with liver cirrhosis have been revised through a PubMed search. Data have been discussed with particular regard to their significance in clinical practice. Expert commentary: The assessment of bacterial translocation and intestinal permeability is not currently used in clinical practice but may be useful to stratify patients' prognosis.