Correlation between the interleukin-36 subfamily and gut microbiota in patients with liver cirrhosis: Implications for gut-liver axis imbalance

Abstract

Background: Liver cirrhosis (LC) affect millions of people worldwide. The pathogenesis of cirrhosis involves complex interactions between immune responses and gut microbiota. Recent studies have highlighted the role of the interleukin-36 (IL-36) subfamily in inflammation and immune regulation. However, the relationship between serum IL-36 subfamily levels and gut microbiota in cirrhosis patients remains unclear. This study aimed to explore the clinical significance of serum IL-36 subfamily levels and their association with gut microbiota in cirrhosis patients.

Aim: To explore the clinical significance of serum IL-36 subfamily levels and their relationship with gut microbiota among cirrhosis patients.

Methods: Sixty-one cirrhosis patients were enrolled from Lihuili Hospital of Ningbo University from May 2022 to November 2023 as the LC group and 29 healthy volunteers as the healthy control (HC) group. The serum expressions of IL-36α, IL-36β, IL-36γ, IL-36Ra, and IL-38 were measured through ELISA, while 16S rRNA gene sequencing was employed to rate microbial community in human fecal samples.

Results: The serum levels of IL-36α, IL-36γ, IL-36Ra, and IL-38 in the LC group remarkably exceeded those in the HC group (P < 0.05). IL-36α, IL-36γ, and IL-38 were related positively to the Child-Pugh score (P < 0.05) and prominently exceeded those in the Child-Pugh C group (P < 0.05). The absolute abundance of harmful bacteria (Bacteroides, Bifidobacterium, Faecalibacterium) remarkably rose, while the beneficial bacteria (Firmicutes, Bacteroides, Escherichia-Shigella) notably decreased in the LC group (P < 0.05). IL-36α, IL-36γ, and IL-38 related positively to Lactobacillus (P < 0.05), while IL-38 negatively related to Fusicatenibacter (P < 0.05).

Conclusion: IL-36γ and IL-38 show promise as potential biomarkers for LC progression, but further validation is required.

Keywords: Gut microbiota; Interleukin-36; Interleukin-36γ; Interleukin-38; Liver cirrhosis.

Figure 1

Serum interleukin-36 subfamily levels in liver cirrhosis patients and healthy controls, and their correlation with Child-Pugh scores. A: Serum interleukin-36 (IL-36) subfamily cytokine levels of patients in the liver cirrhosis (LC) and healthy control groups; B: Serum IL-36 subfamily cytokine levels in the LC group with Child-Pugh Scores. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001. LC: Liver cirrhosis; IL: Interleukin.

Figure 2

Analysis of the differential gut microbiota in liver cirrhosis patients and healthy controls. A: Alpha diversity boxplot between the healthy control (HC) and liver cirrhosis (LC) groups. The blue and orange boxplots represent the HC and LC groups, respectively. Each boxplot displays five sample statistics, with the five lines from top to bottom representing the maximum, 75^th percentile, median, 25^th percentile, and minimum. Dots indicate outliers. A P-value of < 0.05 indicates a statistically significant difference between the two groups; B: Principal coordinates analysis (PCoA): The first two component scores of PCoA1 and PCoA2 are 5.98% and 4.45%, respectively. Non-metric multidimensional scaling (NMDS): An NMDS analysis is considered reliable when the STRESS value is < 0.2; C: Rarefaction Curves: The blue and orange solid lines represent the HC and LC groups, respectively. The rarefaction curves level off, indicating that the sampling in this study is sufficient and the sequencing depth adequately covers all species in the samples, reflecting most of the gut microbiota information; D: Analysis of the absolute quantification and compositional differences of gut microbiota at the phylum level between the HC and LC groups; E: Analysis of the absolute quantification and compositional differences of gut microbiota at the genus level between the HC and LC groups. x- and y-axes represent the groups and abundance values, respectively. Each color in the figure represents a species, with the corresponding species identified by the color legend on the right side of the bar chart. HC: Healthy controls; LC: Liver cirrhosis.

Figure 3

Heatmap of the correlation analysis between the interleukin-36 subfamily and gut microbiota. A: Heatmap of the correlation analysis between the interleukin-36 (IL-36) subfamily and gut microbiota at the phylum level; B: Heatmap of the correlation analysis between the IL-36 subfamily and gut microbiota at the genus level. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001. IL: Interleukin.