| Pentatrichomonas hominis(P.hominis)is a potential zoonotic parasite that can parasitize the cecum of humans,dogs,cats,and non-primate species.The initial research believed that P.hominis is a host intestinal commensal protozoan with no pathogenicity,but recent studies have found that the infection of P.hominis can cause diarrhea in humans,dogs,and cats.Furthermore,the infection rate of P.hominis is higher among patients with gastrointestinal cancers in the epidemiological surveys,so it may be related to the occurrence and development of tumors.Whether P.hominis is pathogenic or not,and whether the infection of P.hominis is associated with host immune status have not been reported.In addition,it was found that parasitic infection can cause changes in intestinal flora,and intestinal flora plays an important role in parasitic pathogenesis.So further in-depth research is needed on the impact of infection of P.hominis in the gut microbiota.Therefore,In this study,wild-type mice with Balb/c and immunodeficient mice with Balb/c Nude were selected as experimental mouse models and infected with P.hominis by oral gavage to investigate its susceptibility and pathogenicity to hosts with different immune status and its effect on intestinal flora of hosts with different immune status.In this study,wild-type mice Balb/c and immunodeficient mice Balb/c Nude were selected as experimental mouse models and infected with P.hominis by oral gavage to investigate its susceptibility and pathogenicity to different immune status hosts and its effect on the intestinal flora of different immune status hosts.This study was conducted to investigate the clinical significance of infection with P.hominis and to further understand the relationship between P.hominis and disease.Susceptibility of Balb/c and Balb/c Nude mice to different doses of P.hominis:Four-week-old Balb/c and Balb/c Nude mice were infected with different numbers of P.hominis,0,1,10,1×10~2,1×10~3,1×10~4,1×10~5,1×10~6,and 1×10~7trophozoites,which were subjected to fecal examination and nested PCR amplification to determine infection,and were tested for body weight for 30 d.Histopathological observations were conducted on the cecum and colon at 30 d after infection.The results show that:(1)The body weight test revealed that the body weight growth rate in the 1×10~6 and 1×10~7 dose groups of Balb/c mice and the 1×10~4,1×10~5,1×10~6 and 1×10~7 dose groups of Balb/c Nude mice was significantly lower than that of the uninfected mice(P<0.05).(2)The infection of P.hominis test showed the minimum infective doses of Balb/c and Balb/c Nude mice is 1×10~6 and 1×10~4trophozoites,respectively.(3)The pathological histological observation revealed that the difference in pathological tissue scores between the cecum and colon of Balb/c Nude mice in the 1×10~4 and 1×10~5 dose groups was highly significant(P<0.001)compared with Balb/c mice,and the intestinal damage was severe,which showed inflammatory infiltration such as epithelial lymphocytes in the mucosal layer and intestinal villi.This indicates that Balb/c Nude mice are more susceptible to P.hominis than Balb/c mice.Pathogenicity of P.hominis infection at different times in Balb/c and Balb/c Nude mice:Four-week-old Balb/c and Balb/c Nude mice were infected with P.hominis with 1×10~6 dose and detected the pattern of trophozoite excretion for 30 days continuously.At four time points 15,30,60,and 90 days after infection,body weight test,morphological and pathological histological observation of cecum and colorectal appearance,as well as cytokines such as IL-6,IL-10,IL-12,TNF-αand Ig A assay were performed.On the 90th day of infection with P.hominis,the viscus organs of mice were observed for appearance morphology and pathological histology,and the number of Goblet cell,the rate of cell proliferation and apoptosis in cecum and colorectal were also detected.The results showed that(1)Both Balb/c and Balb/c Nude mice have two peak excretion times within 30 d.Balb/c mice showed peak excretion times on 11 d and 25 d;Balb/c Nude mice showed peak excretion times on12 d and 20 d.Balb/c Nude mice showed earlier excretion times than Balb/c mice.(2)Body weight test showed that both Balb/c and Balb/c Nude mice had significantly lower body weight growth rates in the infected group than in the uninfected group(P<0.05),but Balb/c Nude mice had significantly lower body weight growth rates than Balb/c mice(P<0.01).(3)The morphological appearance of viscus organs and histopathological observation of cecum and colon showed that Balb/c and Balb/c Nude mice had inflammatory infiltration of epithelial lymphocytes and other inflammatory infiltrates in the cecum and colon at 15 d,and the pathological tissue score of the colon was significantly higher in the Balb/c Nude infected group than in the Balb/c infected group(P<0.001),and the intestinal damage was more serious;at30 d and 60 d,inflammatory infiltration of epithelial lymphocytes was observed in the cecum and colon,partial crypt were lost,and some intestinal villi in the upper layer were damaged;at 90 d,dilute stools were seen in the large intestine of Balb/c and Balb/c Nude infected mice,the crypt and intestinal villi in the cecum and colon were lost,the muscle layer was thinned,and the intestinal tract was severely damaged.Increased intestinal pathology with increasing time of the infection of P.hominis.(4)Cytokine assays indicated the pro-inflammatory factors IL-6,IL-12 and TNF-αin Balb/c and Balb/c Nude infected mice were invreased compared to uninfected group,and the increased secretion of pro-inflammatory factors may exacerbate intestinal inflammation.(5)The number of Goblet cell was significantly increased in the infected group of Balb/c and Balb/c Nude mice compared to the uninfected group of mice in the cecum and colon,suggesting that when infected with P.hominis,goblet cell secrete mucin to resist intestinal mucosal inflammation.(6)Apoptosis and proliferation tests illustrated highly significant differences in apoptosis and proliferation rates in Balb/c and Balb/c Nude infected groups compared with uninfected groups(P<0.001).The apoptosis detection showed that the apoptosis rate of cecum tissue cells in Balb/c Nude mice infected group was 68.93%,which was significantly different than Balb/c mice(P<0.05),and there was no significant difference in the apoptosis rate of colon tissue cells(P<0.05).the Cell proliferation detection showed no significant difference in cecum tissue cell proliferation rate between Balb/c and Balb/c Nude mice infected groups(P>0.05),and 42.58%of colon tissue cells proliferation rate,which was significantly different than Balb/c mice(P<0.05).In conclusion,infection of Balb/c and Balb/c Nude mice with P.hominis promoted apoptosis and proliferation in their cecum and colon,thus causing mucosal barrier damage in mice,and the apoptosis and proliferation rates were higher in Balb/c Nude mice than in Balb/c mice,mucosal damage was more severe in Balb/c Nude mice than in Balb/c mice.In conclusion,the infection with P.hominis has strong pathogenicity to mice with different immune function states,but has stronger pathogenicity to Balb/c Nude immune deficient mice.The effect of P.hominis infection on the gut microbiota of Balb/c and Balb/c Nude mice:The changes of intestinal flora in fecal samples of Balb/c and Balb/c Nude mice infected with P.hominis for 90 days were analyzed by 16Sr DNA high-throughput sequencing for ASV abundance analysis,Alpha and Beta diversity analysis,species and significance analysis The results showed that(1)ASV abundance,Alpha and Beta diversity:the species abundance and composition of the intestinal flora in the Balb/c and Balb/c Nude mice infected groups were significantly increased compared to the uninfected group(P<0.05).(2)Species and significance analysis:the dominant phylum of Balb/c and Balb/c Nude mice was Bacteroidota and Firmicutes,and the abundance of intestinal flora was significantly reduced after infection(P<0.05);the dominant genus was Muribaculaceae＿unclassified genus.The abundance of probiotic bacteria such as Bacteroides and Muribaculum decreased after infection,and the increased abundance of pathogenic bacteria such as Ruminococcaceae and Lachnospiraceae,may associated with cancer and colitis.This indicates that mice infected with P.hominis decreased the abundance of intestinal probiotics,increased the abundance of pathogenic bacteria.It suggests that the pathogenicity of P.hominis in mice may be related to the changes of intestinal flora.In summary,this experiment investigated wild-type mice Balb/c and immunodeficient mice Balb/c Nude were selected as experimental mouse models and infected with P.hominis by oral gavage to investigate its susceptibility and pathogenicity to different immune status hosts and its effect on the intestinal flora of different immune status hosts.We found that the infected with P.hominis for Balb/c Nude mice with immune function deficiency was more susceptible and pathogenic than Balb/c mice,with severe damage to the intestinal mucosal barrier;the significant differences in changes in intestinal flora between the infected and Balb/c Nude mice compared to the uninfected group,with decreased abundance of probiotic bacteria and increased abundance of pathogenic bacteria It suggests that the pathogenicity of P.hominis in mice may be related to the changes of intestinal flora.This experiment is useful for exploring the clinical significance of infection of P.hominis and for providing insight into the relationship between P.hominis and disease. |
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