Acute-on-chronic liver disease enhances phenylephrine-induced endothelial nitric oxide release in rat mesenteric resistance arteries through enhanced PKA, PI3K/AKT and cGMP signalling pathways

Rifaximin treatment shapes a unique metagenome-metabolism network in patients with decompensated cirrhosis

BACKGROUND

Patients with decompensated cirrhosis face poor prognosis and increased mortality risk. Rifaximin, a non-absorbable antibiotic, has been shown to have beneficial effects in preventing complications and improving survival in these patients. However, the underlying mechanisms of rifaximin's effects remain unclear.

METHODS

We obtained fecal samples from decompensated cirrhotic patients undergoing rifaximin treatment and controls, both at baseline and after 6 months of treatment. Shotgun metagenome sequencing profiled the gut microbiome, and untargeted metabolomics analyzed fecal metabolites. Linear discriminant and partial least squares discrimination analyses were used to identify differing species and metabolites between rifaximin-treated patients and controls.

RESULTS

Forty-two patients were enrolled and divided into two groups (26 patients in the rifaximin group and 16 patients in the control group). The gut microbiome's beta diversity changed in the rifaximin group but remained unaffected in the control group. We observed 44 species with reduced abundance in the rifaximin group, including Streptococcus_salivarius, Streptococcus_vestibularis, Haemophilus_parainfluenzae, etc. compared to only four in the control group. Additionally, six species were enriched in the rifaximin group, including Eubacterium_sp._CAG:248, Prevotella_sp._CAG:604, etc., and 14 in the control group. Furthermore, rifaximin modulated different microbial functions compared to the control. Seventeen microbiome-related metabolites were altered due to rifaximin, while six were altered in the control group.

CONCLUSION

Our study revealed distinct microbiome-metabolite networks regulated by rifaximin intervention in patients with decompensated cirrhosis. These findings suggest that targeting these specific metabolites or related bacteria might be a potential therapeutic strategy for decompensated cirrhosis.

Definition and classification of acute-on-chronic liver diseases

Patients with chronic liver diseases (CLDs) develop acute liver injury and/or acute decompensation under the attack of various precipitants and present with significantly elevated alanine aminotransferase and/or total bilirubin levels, liver failure, or acute decompensation of liver cirrhosis, which is called acute-on-CLD (AoCLD). AoCLD accounts for the majority of patients hospitalized in the Department of Hepatology or Infectious Diseases. AoCLD is complicated by various clinical types, the severity of the disease, and may pose a high risk of death. To date, the definition of AoCLD is still vague, and a consensus concept of the clinical classification is lacking. This review aimed to define the concept and clinical types of AoCLD based on related studies and the literature.

A Blunted Sympathetic Function and an Enhanced Nitrergic Activity Contribute to Reduce Mesenteric Resistance in Hyperthyroidism

We aimed to determine whether an experimental model of hyperthyroidism could alter the function of sympathetic and nitrergic components of mesenteric innervation. For this purpose, male Wistar rats were divided into (1) control rats (CT) and (2) rats infused with L-Thyroxine (HT). Body weight gain and adipose tissue accumulation were lower in HT rats, while systolic blood pressure and citrate synthase activity in the soleus muscle were increased by HT. In segments from the superior mesenteric artery, the application of an electrical field stimulation (EFS) induced a vasoconstrictor response, which was lower in arteries from HT animals. The alpha-adrenoceptor antagonist phentolamine diminished EFS-induced vasoconstriction to a lower extent in HT arteries, while the purinergic receptor antagonist suramin reduced contractile response to EFS only in segments from CT. In line with this, noradrenaline release, tyrosine hydroxylase expression and activation and dopamine β hydroxylase expression were diminished in HT. The unspecific nitric oxide synthase (NOS) inhibitor L-NAME increased EFS-induced vasoconstriction more markedly in segments from HT rats. NO release was enhanced in HT, probably due to an enhancement in neuronal NOS activity, in which a hyperactivation of both PKC and PI3K-AKT signaling pathways might play a relevant role. In conclusion, perivascular mesenteric innervation might contribute to reduce the vascular resistance observed in hyperthyroidism.

Hepatic Encephalopathy-Associated Cerebral Vasculopathy in Acute-on-Chronic Liver Failure: Alterations on Endothelial Factor Release and Influence on Cerebrovascular Function

The acute-on-chronic liver failure (ACLF) is a syndrome characterized by liver decompensation, hepatic encephalopathy (HE) and high mortality. We aimed to determine the mechanisms implicated in the development of HE-associated cerebral vasculopathy in a microsurgical liver cholestasis (MHC) model of ACLF. Microsurgical liver cholestasis was induced by ligating and extracting the common bile duct and four bile ducts. Sham-operated and MHC rats were maintained for eight postoperative weeks Bradykinin-induced vasodilation was greater in middle cerebral arteries from MHC rats. Both Nω-Nitro-L-arginine methyl ester and indomethacin diminished bradykinin-induced vasodilation largely in arteries from MHC rats. Nitrite and prostaglandin (PG) F_1α releases were increased, whereas thromboxane (TX) B₂ was not modified in arteries from MHC. Expressions of endothelial nitric oxide synthase (eNOS), inducible NOS, and cyclooxygenase (COX) 2 were augmented, and neuronal NOS (nNOS), COX-1, PGI₂ synthase, and TXA₂S were unmodified. Phosphorylation was augmented for eNOS and unmodified for nNOS. Altogether, these endothelial alterations might collaborate to increase brain blood flow in HE.

Significance of expression of nitric oxide synthetase and cyclooxygenase-2 in different types of gastroesophageal reflux disease

BACKGROUND

Non-erosive reflux disease (NERD), reflux esophagitis (RE), and Barrett's esophagus (BE), the three types of gastroesophageal reflux disease (GERD), have strong independence, and there are certain differences in their clinical manifestations and prognosis. NERD is the most common, but its diagnosis is the most difficult. Reports show that nitric oxide synthetase (NOS) and cyclooxygenase-2 (COX-2) are highly expressed in GERD, but there are few reports on their expression in different types of GERD. It is speculated that NOS and COX-2 have certain value in the diagnosis of NERD.

AIM

To explore the significance of expression of NOS and COX-2 in different types of GRED.

METHODS

From January 2015 to December 2019, 78 GERD patients admitted to the Department of Gastroenterology of our hospital were prospectively selected. According to the type of GERD, they were divided into three groups: NERD, RE, and BE. In addition, 26 healthy people who underwent gastroscopy at the Physical Examination Center of our hospital during the same period were selected as a control group. The expression levels of NOS mRNA and COX-2 mRNA in each group were compared, and the correlation between them was analyzed.

RESULTS

Endoscopic and histopathological examinations showed that in 78 GERD patients, there were 26 cases of RE, 28 cases of NERD, and 24 cases of BE. There was no significant difference in sex or age among the three groups (P > 0.05). The expression levels of NOS mRNA [neuronal nitric oxide synthase (nNOS) mRNA and inducible nitric oxide synthase (iNOS) mRNA] and COX-2 mRNA in the three different types of GERD were significantly higher than those in the control group, and NOS and COX-2 mRNA expression levels in the BE group were significantly higher than those in the control group. The expression levels of NOS mRNA and COX-2 mRNA in the RE group were significantly higher than those in the NERD group (P < 0.05). There was a significant positive correlation between nNOS and iNOS and COX-2 mRNA expression (r = 0.900, 0.897, P < 0.05). Receiver operating characteristic curve analysis showed that the areas under the curves of nNOS mRNA, iNOS mRNA, and COX-2 mRNA in diagnosing NERD were 0.662, 0.671, and 0.613, respectively, which showed no significant difference (P > 0.05). According to the best critical value, when nNOS mRNA expression was higher than 1.505, the sensitivity was 65.8% and the specificity was 89.3%; when iNOS mRNA was higher than 1.795, the sensitivity was 65.8%; when COX-2 mRNA was higher than 1.895, the sensitivity was 55.3% and the specificity was 92.9%.

CONCLUSION

NOS and COX-2 are highly expressed in different types of GRED, and their expression is the highest in BE, followed by RE and NERD. NOS and COX-2 expression may have appreciated value for the diagnosis of NERD.

Beneficial Effect of a Multistrain Synbiotic Prodefen® Plus on the Systemic and Vascular Alterations Associated with Metabolic Syndrome in Rats: The Role of the Neuronal Nitric Oxide Synthase and Protein Kinase A

A high fat diet (HFD) intake is crucial for the development and progression of metabolic syndrome (MtS). Increasing evidence links gut dysbiosis with the metabolic and vascular alterations associated with MtS. Here we studied the use of a combination of various probiotic strains together with a prebiotic (synbiotic) in a commercially available Prodefen® Plus. MtS was induced by HFD (45%) in male Wistar rats. Half of the MtS animals received Prodefen® Plus for 4 weeks. At 12 weeks, we observed an increase in body weight, together with the presence of insulin resistance, liver steatosis, hypertriglyceridemia and hypertension in MtS rats. Prodefen® Plus supplementation did not affect the body weight gain but ameliorated all the MtS-related symptoms. Moreover, the hypertension induced by HFD is caused by a diminished both nitric oxide (NO) functional role and release probably due to a diminished neuronal nitric oxide synthase (nNOS) activation by protein kinase A (PKA) pathway. Prodefen® Plus supplementation for 4 weeks recovered the NO function and release and the systolic blood pressure was returned to normotensive values as a result. Overall, supplementation with Prodefen® Plus could be considered an interesting non-pharmacological approach in MtS.