Basic characteristics of the research subjects

A total of 19 Mongolian patients with liver injury and 26 without liver injury, and 17 Han patients with liver injury and 20 without liver injury were included in this study. There were no significant differences in age, gender, body mass index, marital status, place of residence, smoking status and drinking status between the Han patients with and without liver injury (all P > 0.05). There was no statistical difference between the two groups (all P > 0.05). There were no significant differences in these indicators between the Mongolian and Han populations with liver injury and those without liver injury (all P > 0.05) (see Table 1).

Table 1 Baseline clinical characteristics of respondentsAnalysis of differences in species composition of intestinal microbiota

A total of 5,614,215 high-quality gene sequences from 164 samples were assigned to 19 phyla, 28 classes, 69 orders, 126 families, and 384 genera in the kingdom of bacteria. The number of OTUs contained in these eight groups of samples was analysed, and the results are shown in Fig. 2. The total number of core OTUs in the eight groups was 249. It can be seen that, compared with the T1 and T2 groups, drug treatment led to a decrease in the number of OTUs in both the Mongolian and Han ethnic groups, and the number of OTUs in each group of Mongolian patients was higher than that of the Han patients (see Fig. 2).

Fig. 2

The operational taxonomic unit (OTU) of gut bacteria in various groups

At the phylum level, the intestinal microbiota in each group of the Mongolian and Han patients mainly comprised seven phyla, while at the class level, the intestinal microbiota in each group mainly comprised 10 classes, as shown in Fig. 3. At the order level, the intestinal microbiota in each group mainly comprised 12 orders, while at the family level, the intestinal microbiota in each group mainly comprised 23 families, as shown in Fig. 4. At the genus level, the intestinal microbiota in each group consisted of 45 genera (see Fig. 5).

Fig. 3

The relative abundance of species on phylum level and class level in each group. (left) phylum level. (right) class level

Fig. 4

The relative abundance of species in each group on order level and family level. (left) order level. (right) family level

Fig. 5

The relative abundance of species in each group on genus level

At T1, there were significant differences in 11 taxa between the two groups of Mongolian patients (see Fig. 6). At the genus level, the relative abundances of the genera Ruminococcaceae_UCG_013 and norank_f__Christensenellaceae in the A_LI_T1 group were higher, while those in the A_ULI_T1 group were of Catenibacterium. The relative abundances of Prevotella_7, Leptotrichia, Gordonibacter and Senegalimassilia were relatively high. At T2, there were significant differences in 16 taxa between the two groups. The genera Erysipelatoclostridium and Stenotrophomonas showed higher relative abundances in the A_LI_T2 group, while the relative abundances of the genera Akkermansia, Lachnoclostridium, Hungatella, Clostridioides, Renibacterium and unclassified_f__Desulfovibrionaceae in the A_ULI_T2 group were higher than those in the A_LI_T2 group. High. At T2, new differential bacterial genera (Erysipelatoclostridium, Stenotrophomonas, Akkermansia, Lachnoclostridium, Hungatella, Clostridioides, Renibacterium and unclassified_f__Desulfovibrionaceae) appeared in the LI group and the ULI group.

Fig. 6

Gut bacteria differences between liver injury and non-liver injury groups of the Mongolian. A Cladogram in T1. B Linear discriminant analysis Effect Size (LEfSe) in T1. C Cladogram in T2. D Linear discriminant analysis Effect Size (LEfSe) in T2

The LEfSe analysis showed that a total of 16 taxa were significantly different between T1 and T2 in the LI group (P < 0.05, LDA > 2) (Fig. 7), and all were significantly enriched at T1. At the genus level, the genera Akkermansia, norank_f__Clostridiales_vadinBB60_group, Lachnospiraceae_FCS020_group, Ruminiclostridium, norank_f__Christensenellaceae, Oxalobacter and Leptotrichia were mainly enriched. In contrast, 19 taxa differed significantly between T1 and T2 in the ULI group. At the genus level, the genera Akkermansia, Ruminococcaceae_UCG_002, UBA1819, Campylobacter, Ruminococcaceae_UCG_010, Ruminococcaceae_UCG_011, Stenotrophomonas, Coprobacter, Eubacterium__ruminantium_group, and Enhydrobacter were significantly enriched at T1. The genera Lachnoclostridium, Ruminococcus_2 and Ruminococcaceae_UCG_014 were significantly enriched at T2. The longitudinal analysis showed that three genera, Akkermansia, Stenotrophomonas and Lachnoclostridium, were the genera with differences in the longitudinal changes of medication in Mongolian patients as well as in A_LI_T2 and A_ULI_T2.

Fig. 7

The dynamic difference of the gut bacteria liver injury and non-liver injury groups of the Mongolian from T1 to T2. A Cladogram in gut bacteria liver injury group. B Linear discriminant analysis Effect Size (LEfSe) in in gut bacteria liver injury group. C Cladogram in non-liver injury groups. D Linear discriminant analysis Effect Size (LEfSe) in non-liver injury groups

Similarly, we analysed the Han patients at T1, and 20 taxa were significantly different between the two groups (Fig. 8). At the genus level, Alistipes, Christensenellaceae_R_7_group, CAG_56, rare small. The relative abundances of the genera Subdoligranulum, Fusicatenibacter, norank_f__Christensenellaceae, Ruminococcaceae_UCG_010, Granulicatella, unclassified_f__Ruminococcaceae, Ruminococcaceae_UCG_002, Ruminococcaceae_UCG_014, Dielma, and B_ULI_T1, diocese, Terrispocaliarobacter. The relative abundance of the genus was high. At T2, there were significant differences in 14 taxa between the two groups. The genera Erysipelatoclostridium and Ruminococcus__gnavus_group all showed higher relative abundance in the B_LI_T2 group, while the relative abundances of Akkermansia, Clostridioides, UBA1819, Veillonella, Clostridium__innocuum_group and Flavonifractor were higher in the B_ULI_T2 group. At T2, new differential bacterial genera appeared in both the LI group and the ULI group: Erysipelatoclostridium, Ruminococcus__gnavus_group, Akkermansia, Clostridioides, UBA1819, Veillonella, Clostridium__innocuum_group and Flavonifractor.

Fig. 8

Differences in gut bacteria between liver injury and non-liver injury groups of the Han ethnic. A Cladogram in T1. B Linear discriminant analysis Effect Size (LEfSe) in T1. C Cladogram in T2. D Linear discriminant analysis Effect Size (LEfSe) in T2

The LEfSe analysis showed that a total of 15 taxa were significantly different between T1 and T2 in the LI group (P < 0.05, LDA > 2) (Fig. 9).

Fig. 9

Dynamic difference of gut bacteria from T1 to T2 in liver injury and non-liver injury groups of Han nationality. A Cladogram in gut bacteria liver injury group. B Linear discriminant analysis Effect Size (LEfSe) in in gut bacteria liver injury group. C Cladogram in non-liver injury groups. D Linear discriminant analysis Effect Size (LEfSe) in non-liver injury groups

At T1, the genera Christensenellaceae_R_7_group, norank_f__Ruminococcaceae, F0332, Ruminococcaceae_UCG_014, Ruminococcaceae_UCG_005, Subdoligranulum and Akkermansia were significantly enriched at the genus level. At T2, the genera Ruminococcaceae_NK4A214_group, Coprococcus_3 and Clostridium_sensu_stricto_1 were more abundant. In contrast, 19 taxa differed significantly between T1 and T2 in the ULI group. At the genus level, Akkermansia, Ruminococcus__gnavus_group, Terrisporobacter, Granulicatella, Allisonella and Streptococcus were significantly enriched at T1, while Veillonella, Anaerofilum, Shuttleworthia and the genus unclassified_f__Veillonellaceae were significantly enriched at T2. A longitudinal analysis showed that the genera Akkermansia, Veillonella and Ruminococcus__gnavus_group not only showed differences in longitudinal changes in Han patients after medication but also in the B_LI_T2 and B_ULI_T2 groups.

Notably, we compared the co-differential genera of the intestinal microbiota of the Mongolian and Han LI and ULI groups and found that Akkermansia showed consistent temporal changes in the two groups. From T1 to T2, the beneficial bacteria Akkermansia were significantly reduced in the Mongolian and Han ethnic groups in the LI group and the ULI group. Compared with the ULI group, the reduction in the LI group was more significant. In addition, we found that, although there was no statistical difference in longitudinal changes, the harmful genus Erysipelatoclostridium was higher in abundance in the Mongolian A_LI_T2 and Han B_LI_T2 groups than in those without liver injury.

Correlation analysis of differential bacteria and serum liver function and inflammatory indexes

The correlation results showed that the Mongolian Akkermansia was negatively correlated with ALT, AST, ALP and TNF-α (all P < 0.05), and Stenotrophomonas was positively correlated with ALT, AST, ALP, TBIL and TNF-α (all P < 0.05). The genus Akkermansia in the Han nationality was negatively correlated with ALT, AST, ALP and IL-6 (all P < 0.05), and the genus Ruminococcus_gnavus_group was positively correlated with ALT, AST and IL-6 (all P < 0.05) (see Table 2 and Table 3).

Table 2 Correlation analysis of different gut bacteria and Serological Index in Mongolian Nationality PatientsTable 3 Correlation analysis of different gut bacteria and Serological Index in Han Nationality Patients