This article is part of our May 2021 special issue. Download the full issue here.
Reference
Macnaughtan J, Figorilli F, García-López E, et al. A double-blind, randomized placebo-controlled trial of probiotic Lactobacillus casei Shirota in stable cirrhotic patients. Nutrients. 2020;12(6):1651.
Study Objective
To ascertain if probiotic Lactobacillus casei Shirota (LcS) positively impacts neutrophil function and rates of infection in patients with liver cirrhosis versus a placebo
Design
A double-blind, randomized and placebo-controlled trial at 2 hospitals in the United Kingdom
Participants
Investigators screened 110 patients and included 92 with cirrhosis of any etiology at 2 hospitals. These patients presented with relevant clinical findings consistent with a cirrhosis diagnosis as well as a Child-Pugh score less than 10. Patients were between ages 18 and 78 years and had abstained from alcohol consumption for 2 weeks preceding screening. They were randomly assigned (1:1) to either the intervention or placebo group being stratified for alcoholic and nonalcoholic cirrhosis etiology.
Exclusion criteria included:
- Child-Pugh score >10
- Active infection
- Antibiotic treatment 7 days prior to enrollment
- Gastrointestinal hemorrhage
- Use of immunomodulating agents
- Use of proton pump inhibitors
- Use of pre-, pro-, or synbiotics
- Creatinine >150 mmol/L
- Hepatic encephalopathy II-IV
- Pancreatitis
- Organ failure
- Hepatic malignancy
- Pregnancy
Study Parameters Assessed
Patients in the intervention group received a 65-mL bottle of a LcS drink that yielded a 6.5 billion colony-forming-unit (CFU) bacteria (Yakult Europe) content, to be taken 3 times per day for 6 months. The placebo group was given a similar-looking and similar-tasting drink yielding no bacteria. Patients received 45 bottles every 2 weeks, with the empty, consumed bottles being a measure of compliance. Investigators recorded clinical benchmarks inclusive of blood and biochemical testing at screening, days 0 and 14, and months 1, 3, and 6. They gathered analytes relevant to intestinal hyperpermeability at months 0, 1, and 6.
Primary Outcome Measures
One of the primary endpoints in this study was the change in neutrophil function. Investigators evaluated this using isolation and coincubation methods to measure reactive oxygen species (ROS) production and prevalence of phagocytosis. The additional primary endpoint included incidence of infection, evaluated through routine clinical blood chemistry.
Secondary outcomes included plasma cytokine profile concentration at various intervals, concluding at 6 months. Investigators evaluated intestinal hyperpermeability using urinary lactulose rhamnose ratio, venous endotoxin concentrations, and bacterial DNA identification with polymerase chain reaction (PCR) testing. The final secondary outcome was the quality-of-life assessment, which was accomplished with the use of the standardized SF-36 tool.
Key Findings
Overall, no significant differences in neutrophil function were observed between the intervention and placebo groups. For patients with atypical neutrophil function at the study’s onset, the 6-month LcS treatment yielded a significantly higher ROS production outcome compared to the placebo arm [1403(1214–1821) versus 1168.00(1014–1266), P=0.02]. This is suggestive of improved neutrophil function in that subset.
No significant changes in infection episodes were noted between randomized groups at the end of the study. Intestinal hyperpermeability was also observed to be in a normal range in both groups, with bacterial DNA positivity being 10.1% (placebo group) and 8.1% (LcS group).
The most important outcome is that of a positive change in cytokine profile in all participants in the LcS group of the study.
Outcomes with plasma cytokine concentrations were not significantly different in the vast majority of specific cytokines evaluated in the study. It was observed that LcS lowered median plasma interleukin 1 beta (IL1B; P=0.04) and monocyte chemotactic protein-1(MCP-1; P=0.04) concentration in the alcoholic subset. Further observation revealed a lowered interleukin 17A (IL17A) concentration in the nonalcoholic cohort (P=0.02). Macrophage inflammatory protein-1 beta (MIP-1β) concentrations were lowered in the LcS as a whole at the 6-month interval (P=0.04).
The 36-Item Short Form Health Survey (SF-36) scores assessing quality of life showed no significant differences between either arm of the study.
Practice Implications
In the ever-evolving landscape of understanding the role of the human gut microbiome, a significant portion of the clinical and scientific dialogue has turned to the role played between the gut and the immune system.1 This dialogue extends into the physiological mechanisms of chronic alcohol consumption and the impact it has on the gut microbiome. This, in turn, brings forth a body of evidence elucidating mechanisms of how altered flora contribute to alcohol-associated liver disease.2
Given that, in cases of liver cirrhosis, an imbalance in the gut microbiome has been observed, the progression of inquiry in this study is logical and intriguing. This logic is now juxtaposed in another body of thought that postulates that gut dysbiosis can be implicated in alcoholic liver diseases. The health of the gut microbiome is crucial as dysbiosis results in intestinal inflammation and liver injury, and the subsequent restoration of microbiota, using approaches such as promoting commensal bacterial abundance, could be beneficial in alleviating disease progression.3
The investigators in this study aspire to further establish if LcS can impact immune function to ultimately translate to therapeutic benefit from probiotic use in patients with cirrhosis, both alcoholic and nonalcoholic. This was motivated by previous evidence of LcS, in a smaller study, suggesting a positive correlation.4 While the trial concludes that 1 specific mechanism of action, neutrophil activation, is not notably impacted, it is important to note that a subset of the participants was positively impacted. Those who presented with a lower-than-normal baseline function of neutrophil activity saw this activity improve to more normal and expected levels. This is consistent with the aforementioned open-label pilot study.4 No adverse effects were observed, and there was no increase in infections in all 92 participants, which speaks to the safety of LcS in this patient demographic.
The most important outcome is that of a positive change in cytokine profile in all participants in the LcS group of the study. This suggests that a restoration of gut health creates a downregulation of inflammatory cytokines; however, the mechanism of action appears to be independent of factors related to intestinal hyperpermeability. This raises more questions for potential studies in the future.
Areas of further inquiry, both in the realm of clinical practice as well as study design, bring a number of additional issues to the forefront. Are all probiotics created equal in quality, and does this impact outcomes? Clinical practitioners will suggest that their patient outcomes are proof of this concept and that reputable sources of therapeutic probiotics need to be given consideration. Secondly, the singularity or diversity of probiotic species should be given deliberation as a growing body of evidence suggests diversity of the gut microbiome is correlated with improved health outcomes.5 To this end, consideration should be given to methodologies for gastrointestinal (GI) biome mapping, stool culturing, and other objective evaluations of gut microbiome. Lastly, the dose-dependent effect must be taken into account when selecting therapeutic probiotics and their ability to yield desired CFUs. Clinical observations and case studies suggest that higher-CFU interventions correlate with improved outcomes; however, clear cautions and contraindications exist, and the “more is better” approach has its risks and limitations.6 GI mapping becomes a critical tool in this consideration as well.
Clinicians have several emerging bodies of scholarly evidence and clinical outcomes to reconcile in the implementation of probiotics and the restoration of gut microbiota. Clearly the benefits of doing so are inclusive of, but not limited to, improved hepatic health and immune function.
