Therapeutic potential and mechanisms of Rifaximin in ameliorating iron overload-induced ferroptosis and liver fibrosis in vivo and in vitro.

Liver fibrosis could progress to liver cirrhosis with several contributing factors, one being iron overload which triggers ferroptosis, a form of regulated cell death. Rifaximin, a non-absorbable antibiotic, has shown promise in mitigating fibrosis, primarily by modulating gut microbiota. This study investigated the effects and mechanisms of rifaximin on iron overload-related hepatic fibrosis and ferroptosis. In an iron overload-induced liver fibrosis model in mice and in ferric ammonium citrate (FAC)-stimulated primary hepatocytes, treatment with rifaximin showed significant therapeutic effects. Specifically, it ameliorated the processes of ferroptosis triggered by iron overload, reduced liver injury, and alleviated fibrosis. This was demonstrated by decreased iron accumulation in the liver, improved liver function, and reduced fibrotic area and collagen deposition. Rifaximin also modulated key proteins related to iron homeostasis and ferroptosis, including reduced expression of TFR1, a protein facilitating cellular iron uptake, and increased expression of Fpn and FTH, proteins involved in iron export and storage. In the context of oxidative stress, rifaximin treatment led to a decrease in lipid peroxidation, evidenced by reduced levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and an increase in the reduced glutathione (GSH) and decrease in oxidized glutathione (GSSG). Notably, rifaximin's potential functions were associated with the TGF-ß pathway, evidenced by suppressed Tgfb1 protein levels and ratios of phosphorylated to total Smad2 and Smad3, whereas increased Smad7 phosphorylation. These findings indicate rifaximin's therapeutic potential in managing liver fibrosis by modulating the TGF-ß pathway and reducing iron overload-induced damage. Further research is required to confirm these results and explore their clinical implications.

Open-Label Randomized Controlled Study of Ciprofloxacin vs Rifaximin as Neutropenia Prophylaxis in Allogeneic Hematopoietic Stem Cell Transplantation.

Loss of microbiota diversity has been clearly associated with poor outcomes in the allogeneic hematopoietic stem cell transplantation setting. However, the choice of the optimal antibiotic prophylaxis during the pre-engraftment phase remains unclear. We designed a prospective randomized study to compare our standard-of-care neutropenia prophylaxis (ciprofloxacin) with rifaximin. We enrolled 38 consecutive adult patients who underwent allogeneic hematopoietic stem cell transplantation setting and were randomly assigned to receive ciprofloxacin (20 patients) or rifaximin (18 patients) at day -1. Pretransplant and transplant characteristics did not differ between groups. Cumulative incidence (CI) of acute graft-vs-host disease grade II to IV and moderate/severe chronic graft-vs-host disease was similar in both groups. With a median follow-up of 13.2 months (range, 6.8-30.2) in surviving patients, the 1-year CI of relapse was 20.8% in ciprofloxacin vs 17.8% in rifaximin (P = .616). Importantly, the 1-year CI of treatment-related mortality was significantly reduced in the ciprofloxacin group (10.2% vs 27.8%, P = .032), leading to higher 1-year overall survival (88.9% vs 74.6%, P = .038). In Cox-regression multivariate analysis, antibiotic prophylaxis remained the only predictor of overall survival, independently of donor type, disease risk index, and moderate/severe chronic graft-vs-host disease. Further studies are needed to assess the effects on microbiota diversity and confirm these outcomes.

Rifaximin Ameliorates Loperamide-Induced Constipation in Rats through the Regulation of Gut Microbiota and Serum Metabolites.

Structural changes in the gut microbiota are closely related to the development of functional constipation, and regulating the gut microbiota can improve constipation. Rifaximin is a poorly absorbed antibiotic beneficial for regulating gut microbiota, but few studies have reported its effects on constipation. The purpose of this study was to investigate the effect of rifaximin on loperamide-induced constipation in SD rats. The results showed that rifaximin improved constipation by increasing serum 5-HT, SP, and the mRNA expression of AQP3, AQP8, and reducing the mRNA expression of TLR2 and TLR4. In addition, rifaximin could regulate the gut microbiota of constipated rats, such as increasing the potentially beneficial bacteria Akkermansia muciniphila and Lactobacillus murinus, reducing the Bifidobacterium pseudolongum. According to metabolomics analysis, many serum metabolites, including bile acids and steroids, were changed in constipated rats and were recovered via rifaximin intervention. In conclusion, rifaximin might improve loperamide-induced constipation in rats by increasing serum excitatory neurotransmitters and neuropeptides, modulating water metabolism, and facilitating intestinal inflammation. Muti-Omics analysis results showed that rifaximin has beneficial regulatory effects on the gut microbiota and serum metabolites in constipated rats, which might play critical roles in alleviating constipation. This study suggests that rifaximin might be a potential strategy for treating constipation.

Rifaximin Prevents Intestinal Barrier Dysfunction and Alleviates Liver Injury in MCT-induced HSOS Mice.

OBJECTIVE: Rifaximin is an effective component of treatment strategies for liver and intestinal diseases. However, the efficacy of rifaximin in hepatic sinusoidal obstruction syndrome (HSOS) has not been explored. The present study aimed to investigate the efficacy and mechanism of rifaximin in HSOS. METHODS: An HSOS model was established in mice through the administration of monocrotaline (MCT, 800 mg/kg), and part of the HSOS mice were intragastrically administered with rifaximin. Then, the efficacy of rifaximin in HSOS was evaluated based on the liver pathological findings, liver proinflammatory cytokines, and alanine aminotransferase and aspartate aminotransferase levels. The Ussing chamber was used to evaluate the intestinal permeability, and tight junction (TJ) proteins were measured by Western blotting and real-time polymerase chain reaction to evaluate the intestinal barrier integrity. Then, the serum proinflammatory cytokine levels were evaluated by enzyme-linked immunosorbent assay. Afterwards, an in vitro experiment was performed to determine the relationship between rifaximin and TJ proteins. RESULTS: Rifaximin effectively alleviated the MCT-induced HSOS liver injury, suppressed the expression of liver proinflammatory cytokines, and reduced the serum levels of tumor necrosis factor-alpha and interleukin-6. Furthermore, rifaximin reduced the intestinal permeability, improved the intestinal barrier integrity, and promoted the expression of TJ proteins. CONCLUSION: The results revealed that the intestinal barrier integrity was destroyed in MCT-induced HSOS. The significant alleviation of MCT-induced HSOS induced by rifaximin might be correlated to the repairment of intestinal barrier integrity via the regulation of the TJ protein expression.

Rifaximin use favoured micafungin-resistant Candida spp. infections in recipients of allogeneic hematopoietic cell transplantation.

Damage to gut mucosa following conditioning regimens may favour bacterial infections that can trigger graft versus host disease (GvHD) in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Rifaximin, an oral and non-absorbable antibiotic, has been recently proposed as effective prophylaxis to reduce bacterial infections in the gut and consequently acute GvHD in this setting. The present study evaluated safety and outcomes of HSCT patients that were treated with rifaximin prophylaxis at Perugia University Hospital. Rifaximin prophylaxis was introduced as standard of care in HSCT patients in May 2018. We retrieved data from 118 consecutive transplants, and we compared the outcomes of rifaximin-treated patients with historical controls that did not receive antibiotic prophylaxis. While incidences of neutropenic fever, documented bacterial infections, and aGvHD were similar in the two groups, we found an increased frequency of invasive candidiasis and clinically relevant Candida spp. infections in rifaximin-treated patients (5 patients vs 1 patient, 25% [± 0.99%] vs 1% [± 0.01%], p < .0001). Three rifaximin-treated patients experienced life-threating candidemia (2 C. krusei, 1 C. orthopsilosis). Rifaximin was the only factor that increased the risk of Candida spp. infections. Rifaximin could have contributed to microbiome disruption which favoured an outbreak of life-threatening Candida infections. This important complication forced us to halt its use. Larger, prospective studies are needed to assess the impact of rifaximin prophylaxis on incidence of bacterial infections, aGvHD, and survival of HSCT patients.

Impact of Antibiotic Resistance Genes in Gut Microbiome of Patients With Cirrhosis.

BACKGROUND AND AIMS: Cirrhosis is associated with changes in intestinal microbiota that can lead to hepatic encephalopathy (HE) and infections, especially with antibiotic-resistant organisms. However, the impact of gut microbial antibiotic resistance gene (ARG) burden on clinical outcomes is unclear. The aims of the study were to determine the impact of ARGs in cirrhosis-related gut metagenome on outcomes and disease progression, study the effect of rifaximin on ARG burden, and compare ARGs in cirrhosis with chronic kidney disease (CKD) and diabetes. METHODS: In outpatients with cirrhosis who underwent metagenomics, we evaluated change in ARG abundances with progression and their multivariable impact on 90-day hospitalizations and deaths over 1 year. We also studied ARGs pre- and 8 weeks post-rifaximin in patients with compensated cirrhosis in an open-label trial. Finally, ARGs from CKD and diabetes studies were compared with cirrhosis on machine learning. RESULTS: A total of 163 patients with cirrhosis (43 compensated, 20 ascites-only, 30 HE-only, 70 both) and 40 controls were included. ARG abundances were higher in cirrhosis versus controls and worsened with advancing cirrhosis severity; 44 patients were hospitalized and 14 died. ARG abundances were associated with hospitalizations and mortality while controlling for cirrhosis complications, medications, and demographics. Rifaximin trial: ARG abundance patterns were minimally affected in 19 patients post-rifaximin. CKD/diabetes comparison: ARG abundance patterns in cirrhosis are distinguishable on machine learning and include more gram-positive ARGs. CONCLUSIONS: Cirrhosis is associated with high gut microbial ARG gene burden compared with controls, which worsens with disease progression and may be different from CKD and diabetes. ARGs are not affected by rifaximin and are associated with hospitalizations and death.

Fecal bacteria can predict the efficacy of rifaximin in patients with diarrhea-predominant irritable bowel syndrome.

OBJECTIVE: Rifaximin for treating diarrhea-predominant irritable bowel syndrome (IBS-D) by regulating intestinal microbiota has been studied and recommended. In this study, we tried to investigate the effect of rifaximin on different components of intestinal microbiota and explore which component of gut microbiota can predict the efficacy of rifaximin in IBS-D. METHODS: Healthy controls (HC) and IBS-D patients meeting the Rome III criteria were recruited, and IBS-D patients were orally administered 400 mg rifaximin three times daily for 2 weeks. Subjects were tested for small intestinal bacterial overgrowth (SIBO), their symptoms were recorded, and fecal and rectal mucosal samples were collected before and after treatment. Fecal and rectal mucosal bacterial data were obtained via 16S rRNA sequencing, and fecal fungal data were obtained via ITS2 sequencing. RESULTS: IBS-D patients were divided into two subgroups based on fecal bacterial composition, IBS1 (patients whose fecal bacterial composition were different from HC) and IBS0 (patients whose fecal bacterial profiles were similar to HC). Rifaximin increased fecal Bifidobacterium and decreased E. coli and Enterobacter in IBS1 patients. Although rectal mucosal bacteria and fecal fungi were not significantly altered in all patients after rifaximin intervention, rifaximin enhanced the connections among fecal bacteria, mucosal bacteria and fecal fungi in IBS1 patients. Compared with IBS0, we surprisingly found rifaximin ameliorated abdominal symptoms of IBS1 much better. Receiver operating curve analysis revealed patients whose fecal microbial dysbiosis indices (MDI) were higher than -3.006 could be diagnosed as IBS1. CONCLUSION: Fecal bacterial dysbiosis could be a biomarker for rifaximin treatment for IBS-D.

Adherence to Short-course Pharmacotherapy in Adults with Irritable Bowel Syndrome.

Irritable Bowel Syndrome (IBS), characterized by abdominal pain and bowel dysfunction, treatment focuses on alleviating symptoms. Adherence is crucial for pharmacologic management success. We examined 73 adult's objective adherence to rifaximin using the taxonomy for adherence. Demographic, quality of life (QOL), psychological distress, perceived stress, adverse childhood experiences (ACE), pain, and adherence data were collected. Impaired QOL, elevated psychological distress and perceived stress, and a significant number of ACE were reported at baseline. Average time to prescription initiation was 2.5 days. Once implemented, 92% missed midday dose and persisted 5 days beyond the prescribed dose. High-adherers reported lower pain levels post-rifaximin compared to low-adherers. Objective adherence was significantly lower than self-reported. Objective adherence was not predicted by above variables. Adherence to rifaximin is poor in those with IBS. Future research examining perceived barriers/facilitators toward rifaximin adherence may provide insight into patient-centered, modifiable targets for adherence interventions and improve patient-related outcomes.

Safety and Efficacy of Rifaximin in Prophylaxis of Spontaneous Bacterial Peritonitis: A Systematic Review and Meta-analysis.

AIM: The role of rifaximin in the prevention of Spontaneous Bacterial Peritonitis (SBP) is not well studied. The aim of this meta-analysis was to evaluate the role of rifaximin in the prevention of SBP. METHODS: A computerized literature search for relevant clinical trials was conducted during August 2017. Data on Frequency of SBP, the success rate of prevention of SBP, mortality rate, hepatorenal syndrome, septic shock, hepatic encephalopathy, and GIT bleeding were extracted and pooled as Risk Ratio (RR) with their 95% Confidence Interval (CI) in a meta-analysis model. Heterogeneity was assessed by Chi-square test. RESULTS: Six studies involving 973 patients were included in the final analysis. The pooled effect estimate showed that the rifaximin plus norfloxacin group had less incidence of SBP (RR 0.58, 95% CI[0.37, 0.92], P=0.02) and hepatic encephalopathy (RR 0.38, 95% CI[0.17, 0.84], P=0.02) than the norfloxacin-based regimen group. No significant difference between rifaximin and norfloxacin in terms of frequency of SBP and success rate of primary prevention of SBP (RR 0.49, 95% CI [0.24, 1.01], P=0.05; RR1.21, 95% CI [0.95, 1.55], P=0.13, respectively). CONCLUSION: Based on our analysis, Rifaximin is a promising drug and appears to be a good alternative to norfloxacin in the prevention of SBP.

Long-term management of hepatic encephalopathy with lactulose and/or rifaximin: a review of the evidence.

A consolidated overview of evidence for the effectiveness and safety/tolerability of hepatic encephalopathy (HE) treatment over the long term is currently lacking. We identified and assessed published evidence for the long-term (≥6 months) pharmacological management of HE with lactulose and/or rifaximin. A literature search was conducted in PubMed (cutoff date 05 March 2018) using the search terms 'hepatic encephalopathy+rifaximin' and 'hepatic encephalopathy+lactulose'. All articles containing primary clinical data were manually assessed to identify studies in which long-term (≥6 months) effectiveness and/or safety/tolerability end points were reported for lactulose and/or rifaximin. Long-term effectiveness outcomes were reported in eight articles for treatment with lactulose alone and 19 articles for treatment with rifaximin, alone or in combination with lactulose. Long-term safety/tolerability outcomes were reported in six articles for treatment with lactulose alone and nine articles for treatment with rifaximin, alone or in combination with lactulose. These studies showed that lactulose is effective for the prevention of overt HE recurrence over the long term and that the addition of rifaximin to lactulose significantly reduces the risk of overt HE recurrence and HE-related hospitalization, compared with lactulose therapy alone, without compromising tolerability. Current evidence therefore supports recommendations for the use of lactulose therapy for the prevention of overt HE recurrence over the long term, and for the additional benefit of adding rifaximin to lactulose therapy. Addition of rifaximin to standard lactulose therapy may result in substantial reductions in healthcare resource utilization over the long term, by reducing overt HE recurrence and associated rehospitalization.

Double-Blind Placebo-Controlled Study of Rifaximin and Lactulose Hydrogen Breath Test in Gulf War Veterans with Irritable Bowel Syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) occurs in up to 33% of Gulf War (GW) Veterans. Alterations in gut microflora including small intestinal bacterial overgrowth (SIBO) during deployment may play a role in development of IBS. Rifaximin is a minimally absorbed antibiotic speculated to improve IBS symptoms, in part, by restoring normal gut microflora. The aim of this study was to compare rifaximin to placebo on IBS symptoms and quality of life (QOL) in GW Veterans with IBS without constipation. METHODS: A double-blind, placebo-controlled study was performed. One hundred and twenty-two GW Veterans with IBS (Rome III) from our database and referral to gastroenterology and internal medicine clinics were screened. After a 2-week run-in period, 50 patients were randomized (1:1) to receive either rifaximin 550 gm or placebo twice daily for 2 weeks in a double-blind study. Patients were advised not to change their diet or medications during the study. The symptoms assessed were: (1) stool frequency, (2) stool consistency (Bristol stool scale, 1-7, very hard to watery), (3) urgency (1 = yes/0 = no daily for 7 days), (4) severity of abdominal pain (0-4, none to severe), (5) severity of bloating (1-4, none to severe), and (6) global improvement scale (1-7, substantially worse to substantially improved). These were recorded for 7 consecutive days and then averaged across the 7 days, to generate a continuous variable. The symptom data were compared after 2 weeks of treatment. QOL was assessed using IBS-QOL. The lactulose hydrogen breath test (LHBT) was performed at baseline and after 2 weeks of treatment. RESULTS: Fifty Veterans were randomized to receive treatment; 3 withdrew and 3 were lost to follow-up. Data were analyzed from 44 patients (38 men, 6 women, median age 52, range 33-77 years). Rifaximin was not associated with significant improvement in global symptoms, abdominal pain, bloating, stool urgency, frequency, or consistency (all P ≥ 0.25) or QOL (all P ≥ 0.26). Normalization of SIBO by LHBT was not different between rifaximin- and placebo-treated Veterans (7 vs. 22%, P = 0. 54). CONCLUSION: Rifaximin was not effective in improving IBS symptoms and QOL in GW Veterans with non-constipated IBS.

Combination of rifaximin and lactulose improves clinical efficacy and mortality in patients with hepatic encephalopathy.

BACKGROUND: Rifaximin and lactulose are common effective agents for hepatic encephalopathy (HE). Whether a combination of rifaximin and lactulose improves the efficacy and mortality in patients with HE compared with lactulose alone needs to be analyzed. METHODS: A systematic search was performed in electronic databases and other sources for possible studies focusing on combination therapy of rifaximin and lactulose for HE between January 2000 and February 2018. A meta-analysis was performed by the method recommended by the Cochrane Collaboration, and estimated effect size was presented as risk difference (RD), 95% CI, and the number needed to treat (NNT). Subgroup analysis, sensitivity analysis, and Trial Sequence Analysis were comprehensively performed to indicate the source of heterogeneity and risk of bias. RESULTS: Five randomized and five observational studies involving 2,276 patients were included. Combination therapy had a significant advantage in both clinical efficacy increase (RD 0.26, 95% CI 0.19-0.32, NNT 5) and mortality decrease (RD -0.16, 95% CI -0.20-0.11, NNT 9) in overall analysis. In the pooled analysis of randomized studies, combination therapy showed similar results in clinical efficacy (RD 0.25, 95% CI 0.16-0.35, NNT 4) and mortality (RD -0.22, 95% CI -0.33-0.12, NNT 5). Compared with lactulose, hospital stay was also reduced in combination therapy, and there was no significant difference in treatment-related adverse events between the two groups. CONCLUSION: Combination of rifaximin and lactulose has beneficial effects on HE. Compared with lactulose alone, additional rifaximin increases clinical efficacy and decreases mortality. However, its effects on different types of HE are still uncertain.

Rifaximin in nonalcoholic fatty liver disease: hit multiple targets with a single shot.

BACKGROUND/AIMS: The pathogenesis of nonalcoholic fatty liver disease (NAFLD) may include increased insulin resistance, upregulation of proinflammatory cytokines, lipopolysaccharide, and BMI. Rifaximin is a minimally absorbable antibiotic that might act against a broad spectrum of gut bacteria. This study aimed to investigate the effects of rifaximin on NAFLD. PATIENTS AND METHODS: Fifty participants with biopsy-proven nonalcoholic steatohepatitis (NASH) were registered in this multicentric, double-blind, randomized, placebo-controlled study. BMI, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, lipid profile, serum endotoxin, homeostatic model assessment, toll-like receptor-4, interleukin-10 (IL-10), IL-6, tumor necrosis factor-α, and cytokeratin-18 (CK-18) levels were evaluated at baseline and at 1, 3, and 6 months of rifaximin therapy (1100 mg/day). RESULTS: Patients were randomized into two groups (rifaximin group; n=25 and placebo group; n=25). After 6 months of rifaximin therapy, patients with NASH showed a significant reduction in homeostatic model assessment, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase, endotoxin, toll-like receptor-4, IL-6, tumor necrosis factor-α, CK-18, and NAFLD-liver fat score (all P<0.05), but no changes in the lipid profile; moreover, there was a mild nonstatistically significant reduction of BMI. However, in the placebo group, there was no significant difference in these variables at baseline and after therapy. CONCLUSION: Rifaximin therapy appears to be effective and safe in modifying NASH through reduction of serum endotoxin and improvement of insulin resistance, proinflammatory cytokines, CK-18, and NAFLD-liver fat score.

Primary Prophylaxis to Prevent the Development of Hepatic Encephalopathy in Cirrhotic Patients with Acute Variceal Bleeding.

Background and Aim: Variceal bleeding is the second most important precipitating factor related to the development of episodic hepatic encephalopathy; but to date there are no recommendations to prevent this complication. The aim of this study was to compare if primary prophylaxis with lactulose or L-ornithine L-aspartate or rifaximin, in cirrhotic patients with variceal bleeding, is better than placebo for avoiding the development of hepatic encephalopathy. Methods: A randomized, double-blind, placebo-controlled clinical trial (ClinicalTrials.gov identifier: NCT02158182) which included cirrhotic patients with variceal bleeding, without minimal or clinical hepatic encephalopathy at admission. Findings: 87 patients were randomized to one of four groups. The basal characteristics were similar between groups. Comparatively with placebo, the frequency with regard to the development of hepatic encephalopathy was as follows: lactulose (54.5% versus 27.3%; OR = 0.3, 95% CI 0.09-1.0; P = 0.06); L-ornithine L-aspartate (54.5% versus 22.7%, OR = 0.2, 95% CI 0.06-0.88; P = 0.03); rifaximin (54.5% versus 23.8%; OR = 0.3, 95% CI 0.07-0.9; P = 0.04). There was no significant difference between the three groups receiving any antiammonium drug (P = 0.94). In the group receiving lactulose, 59.1% had diarrhea, and 45.5% had abdominal discomfort, bloating, and flatulence. Two patients (10%) treated with lactulose and a patient (4.5%) in the placebo group developed spontaneous bacterial peritonitis due to E. coli; one of them died due to recurrent variceal bleeding. There were no other adverse effects. Conclusions: Antiammonium drugs, particularly L-ornithine L-aspartate and rifaximin, proved to be effective in preventing the development of hepatic encephalopathy in those cirrhotic patients with variceal bleeding.

Antifibrotic and molecular aspects of rifaximin in alcoholic liver disease: study protocol for a randomized controlled trial.

BACKGROUND: Alcoholic liver disease is the leading cause of cirrhosis worldwide. Due to an increase in alcohol overuse, alcoholic liver disease has become an increased burden on health care systems. Abstinence from alcohol remains the cornerstone of alcoholic liver disease treatment; however, this approach is hampered by frequent relapse and lack of specific therapy for treating advanced cases of liver disease. In the present study, we hypothesized that gut microbiota drive the development of liver fibrosis and that modulation of gut microbiota with the gut-selective, nonabsorbable antibiotic rifaximin attenuates alcoholic liver fibrosis. METHODS/DESIGN: Our double-blind, placebo-controlled trial will include 136 participants with biopsy-verified alcoholic fibrosis (Ishak liver fibrosis score of 1-4). Participants are randomized 1:1 to receive placebo or 550 mg of rifaximin twice daily for 18 months. A liver biopsy will be performed at the end of the treatment period to evaluate the effect of drug treatment on liver fibrosis. Stool, urine, and saliva specimens will be collected before treatment begins, at 1 month, and at the end of the treatment period. Fecal samples are used for microbiome deep sequencing. Changes in microbiome composition are compared before and after the trial medication period and linked to changes in liver fibrosis. DISCUSSION: This is the first clinical trial to evaluate the effect of gut microbiota on liver fibrosis in humans. If gut microbiota are an important promoter of alcoholic liver disease, current results may open new therapeutic avenues and revolutionize the current understanding of chronic liver diseases. TRIAL REGISTRATION: EudraCT, 2014-001856-51 . Registered on 16 August 2014.