Parasite for gut health? Singapore researchers find one that suppresses inflammation and improves gut diversity

Based on the findings, the researchers believe that the microorganism could potentially be translated into probiotics to treat inflammation.  

The study was conducted by researchers from the National University of Singapore’s Yong Loo Lin School of Medicine (NUS Medicine), Department of Microbiology and Immunology.

“Our data indicates that Blastocystis ST4 behaves like an ‘ecosystem engineer’ that helps keep the bacterial environment of the gut diverse and versatile, to better combat potential diseases that may arise,” ​said one of the researchers Dr Png Chin Wen.

The parasite was found to have altered the bacteria ecosystem in the gut and promoted quicker recovery from inflammation, based on mice models and experimentally induced colitis.

For instance, there were higher levels of unclassified Clostridia ​vadinBB60 group, Tuzzerella, ​and Peptococcaceae ​uncultured, and lower levels of Odoribacter, ​and Lachnospiraceae ​ASF356 at day seven, in mice colonised with Blastocystis ​subtype ST4 colonisation using oral gavage.

In contrast, Blastocystis ​subtype ST4-free mice had a significant reduction in bacteria such as Lachnospiraceae ​NK4A136 group, Odoribacter, Lachnospiraceae ​uncultured, while Alloprevotella, Bacteroides, ​and Paraprevotella ​were significantly increased.

Colonisation of Blastocystis ​subtype ST4 was also found to enhance the accumulation of Treg and Th2 cells, according to a mice model. Both Treg and Th2 cells play crucial roles in the host’s resistance to parasite infection and limiting intestinal inflammation.

In addition, mice with Blastocystis ​subtype ST4 colonisation showed faster recovery after DSS-induced colitis, as compared to Blastocystis-​free mice.

Findings of the study were published in Cellular and Molecular Life Sciences. ​

Changes in immune cell ​

There were also changes in immune cells activity when the faecal microbiota of ST4-colonised mice was transplanted into DSS-induced colitis mice.

For instance, there was an increased number of CD4+ cells expressing IL-10 – an anti-inflammatory cytokine – and a decreased number of CD4+ cells expressed TNF-alpha – an inflammatory cytokine – in these mice.

“When one thinks of parasites, we do not normally associate them as beneficial organisms. However, the study proved that Blastocystis ST4 is not a pathogen but could in fact promote better health of the gut,” ​Dr Deng Lei, another researcher of the study, said.

Future studies could focus on understanding the mechanistic connection between Blastocystis ​ST4 colonisation, IL-10 signaling, and bacterial-derived SCFAs using relevant animal models, according to the researchers.

Not all are beneficial ​

At the same time, the researchers highlighted that not all the subtypes of Blastocystis ​could be beneficial.

For instance, the subtype 7 (ST7) could cause​ colonic tissue damage and ulceration in DSS-induced colitis mice.

Another subtype, ST3, was found to promote a faster recovery​ from colitis in rats.

As for ST4, which was the subject of the study, it has been found to be prevalent in the European populations, and rarely found in South America, Africa, and Asia.

Source: Cellular and Molecular Life Sciences.​

Experimental colonization with Blastocystis ST4 is associated with protective immune responses and modulation of gut microbiome in a DSS-induced colitis mouse model​

https://doi.org/10.1007/s00018-022-04271-9​

Authors: Deng, L., Wojciech, L., Png, C.W. et al.​