Variations in Gut Microbiome are Associated with Prognosis of Hypertriglyceridemia-Associated Acute Pancreatitis

Abstract

Hypertriglyceridemia-associated acute pancreatitis (HTGAP) is linked with increased severity and morbidity. Intestinal flora plays an important role in the progression of acute pancreatitis (AP). However, pathogenetic association between gut microbiota and HTGAP remains unknown. In this study, we enrolled 30 HTGAP patients and 30 patients with AP that is evoked by other causes. The V3-V4 regions of 16S rRNA sequences of the gut microbiota were analyzed. Clinical characteristics, microbial diversity, taxonomic profile, microbiome composition, microbiological phenotype, and functional pathways were compared between the two groups. Our results showed that the HTGAP group had a higher proportion of severe AP (46.7% vs. 20.0%), organ failure (56.7% vs. 30.0%), and a longer hospital stay (18.0 days vs. 6.5 days). HTGAP group also had poorer microbial diversity, higher abundances of Escherichia/Shigella and Enterococcus, but lower abundances of Dorea longicatena, Blautia wexlerae, and Bacteroides ovatus as compared with non-HTGAP group. Correlation analysis revealed that gut bacterial taxonomic and functional changes were linked with local and systemic complications, ICU admission, and mortality. This study revealed that alterations of gut microbiota were associated with disease severity and poor prognosis in HTGAP patients, indicating a potential pathophysiological link between gut microbiota and hypertriglyceridemia related acute pancreatitis.

Keywords: acute pancreatitis; gut microbiota; hypertriglyceridemia; prognosis.

Figure 1

Alpha and beta diversity analysis between HTGAP and non-HTGAP groups. (a) Alpha diversity based on species richness. (b) Alpha diversity based on Shannon’s diversity index. Box-plot features represent the median (central line), upper and lower quartiles (box), and the maximum and minimum values of the data (bars). (c) Beta diversity analysis based on PCoA plot. The abscissa and ordinate represent the contribution rate of the first principal component (5.392%) and the second principal component (4.403%) to the sample difference. Each symbol represents the gut microbiota of a sample. (d) Rarefaction curve of species richness. HTGAP, hypertriglyceridemia-associated acute pancreatitis; PCoA, principal coordinate analysis.

Figure 2

Relative abundances of bacteria between groups at the phylum (a), family (b), and genus (c) levels. Bacteria that below 1.00% in two groups or cannot be assigned to a specific taxonomic category, were grouped into others. HTGAP, hypertriglyceridemia-associated acute pancreatitis.

Figure 3

Differential ASVs between HTGAP and non-HTGAP groups. ASV, amplicon sequence variants. (a) Volcano plot. Each point represents an ASV, and significantly different ASVs are colored (green = depleted in the non-HTGAP group; red = enriched in the non-HTGAP group; gray = not significantly enriched or depleted). (b) Heatmap. Rows represent discriminative ASVs, and columns represent individual samples. Blue represents lower relative abundances, and red represents higher relative abundances. The taxonomic assignment and level of abundance (enriched or depleted) are provided to the left of the heatmap. (c) Manhattan plot. The x axis represents the microbial ASV taxonomy at class level ranked by alphabetical order, and y axis represents -log10 (p value). Filled triangles, hollow inverted triangles, and solid circles indicate ASVs enriched, depleted, and without significant difference, respectively. The color of each marker represents the different taxonomic affiliation of the ASVs, and the size corresponds to their relative abundances using log2 transformed CPM values. HTGAP, hypertriglyceridemia-associated acute pancreatitis; ASV, amplicon sequence variants; CPM, count per million.

Figure 4

Relative abundances of differential ASVs between HTGAP and non-HTGAP groups. Box-plot features represent the median (central line), upper and lower quartiles (box), and the maximum and minimum values of the data (bars). HTGAP, hypertriglyceridemia-associated acute pancreatitis; ASV, amplicon sequence variants.

Figure 5

Predicted phenotypes and functional pathways of intestinal microflora. (a) Relative abundance of bacteria tolerant of oxidative stress. (b) Relative abundance of bacteria containing mobile elements. (c) Spearman correlations between HTGAP associated ASVs and functional pathways. Blue represents a negative correlation, and red represents a positive correlation. HTGAP, hypertriglyceridemia-associated acute pancreatitis; ASV, amplicon sequence variants. The strength of positive (red) or negative (blue) correlation is shown by two-color heatmap, with asterisks denoting statistical significance (* p < 0.05, ** p < 0.01).

Figure 6

Spearman correlations between differential ASVs and clinical outcomes as well as indicators of disease severity. ASV, amplicon sequence variants; ANC, acute necrotic accumulation; WON, walled-off necrosis; BMI: body mass index; DM, diabetes mellitus; APACHE II: the Acute Physiology and Chronic Health Evaluation II score; APFC, acute peripancreatic fluid collection; MAP: mild acute pancreatitis; MSAP: moderately severe acute pancreatitis; SAP: severe acute pancreatitis; SIRS: systemic inflammatory response syndrome; CRP: C-reactive protein; ICU: intensive care unit; AKI: acute kidney injury; ACS: abdominal compartment syndrome; ARDS: acute respiratory distress syndrome; SOFA: the Sequential Organ Failure Assessment score. The strength of positive (red) or negative (blue) correlation is shown by two-color heatmap, with asterisks denoting statistical significance (* p < 0.05, ** p < 0.01).