Gut microbiota drives the attenuation of dextran sulphate sodium-induced colitis by Huangqin decoction

Abstract

The gut microbiota, including probiotics and pathogenic microorganisms, is involved in ulcerative colitis (UC) by regulating pathogenic microorganisms and the production of intestinal mucosal antibodies. Huangqin decoction (HQD), a traditional Chinese formula chronicled in the Shanghan lun, has been recognized as an effective drug for UC, owing to its anti-inflammatory and anti-oxidative properties. In the present study, we investigated whether HQD ameliorates dextran sulphate sodium (DSS)-induced colitis through alteration of the gut microbiota. We found that HQD significantly inhibited colitis, alleviating the loss of body weight, disease activity index, colon shortening, tissue injury, and inflammatory cytokine changes induced by DSS treatment. Principal component analysis and principal co-ordinate analysis showed an obvious difference among the groups, with increased diversity in the DSS and DSS+HQD groups. Linear discriminant analysis effect size was used to determine differences between the groups. The relative abundance of Lactococcus was higher in the DSS+HQD group than in the DSS group, whereas Desulfovibrio and Helicobacter were decreased. Furthermore, the protective effect of HQD was attenuated only in antibiotic-treated mice. In conclusion, our results suggest that HQD could ameliorate DSS-induced inflammation through alteration of the gut microbiota.

Keywords: Huangqin decoction; gut microbiota; high-throughput sequencing; ulcerative colitis.

Figure 1. Role of HQD against DSS-induced colitis in C57BL/6 mice

(A) Experimental process inducing UC by 3% DSS. (B) Body weight change after 3% DSS induction of colitis. (C) DAI and (D) intestine photograph and statistics of colorectum length in each group. (E) Representative H&E-stained colorectum sections (100× magnification) in mice with acute colitis. Histology score based on ten H&E-stained sections per mouse. (F) Expression levels of TNF-α, IL-1β, IL-6, and COX-2 in colorectum of acute colitis model determined by RT-qPCR. *P < 0.05; **P < 0.01; ***P < 0.001, versus DSS-treated group. Data are presented as mean ± SD of six mice in each group (B-F, n = 6). HQD, Huangqin decoction.

Figure 2. Evaluation of illumina MiSeq sequencing data showing that HQD could modulate the overall structure of gut microbiota

(A) Rarefaction curves determined at the 97% similarity level. (B) Shannon–Wiener curves of samples, calculated using mothur. (C) Venn diagram of OTUs in the three groups. (D) Multiple sample PCA analysis. (E) Multiple sample PCoA analysis. (F) Multiple sample similarity tree. Samples of the control group indicated by a, samples of the DSS group by b, and samples of the DSS+HQD group by c. HQD, Huangqin decoction.

Figure 3. Gut microbial community structure in mice after HQD treatment

(A) Microbial community bar plot by phylum. (B) Microbial community bar plot by class. (C) Microbial community bar plot by order. (D) Microbial community bar plot by family. (E) Microbial community bar plot by genus. Control-a, DSS-b, DSS+HQD-c. HQD, Huangqin decoction.

Figure 4. Difference in dominant microorganisms between groups

(A) Distribution histogram based on LDA. (B) Cladogram. Control-a, DSS-b, DSS+HQD-c. HQD, Huangqin decoction.

Figure 5. Effect of HQD on gut microbial relative abundance in mice

(A) Relative abundance within Bacteroidetes. (B) Relative abundance within Firmicutes. (C) Relative abundance within Proteobacteria. *P < 0.05; **P < 0.01; ***P < 0.001. Data are presented as mean ± SD of five soil samples in each group (A–C, n = 5). HQD, Huangqin decoction.

Figure 6. Effect of HQD against DSS-induced colitis after pretreatment with AB

(A) Experimental process inducing colitis by 3% DSS after pretreatment with AB. (B) Body weight change after 3% DSS induction of colitis after AB. (C) DAI. (D) Statistics of colorectum length in each group. (E) Representative H&E-stained colorectum sections (100× magnification) and Histology score based on ten H&E-stained sections per mouse. *P < 0.05; **P < 0.01; ***P < 0.001. Data are presented as mean ± SD of six soil samples in each group (B-E, n = 6). AB, antibiotic. HQD, Huangqin decoction.